University of Mauritius

Faculty of Engineering

Department of Computer Science & Engineering

Module – Information Technology – CSE 1010e

Week Topic

1 Introduction to IT

2 Tutorial: Chapter 1 and 2

3

4 Tutorial: Chapter 3 and 4

5

6 Tutorial: Chapter 5 and 6

7

8 Tutorial: Chapter 7 and 8

9 Test [up to chapter 7]

10 Tutorial: Chapter 9 and 10

11

12 Tutorial: Chapter 11 and 12

13 Word Processing and Spreadsheet Tests

14 Tutorial: Chapter 13 and Revision

15

The table shown above should only be taken as a guide.

For this module:

Minimum 8 tutorial sessions covering 13 Chapters

Practicals after each Chapter (Students responsible for working practicals in labs or at

home)

Course Work + Exams

Course Work - 40%

o 1 class test (Week 9 covering chapters 1 – 7) - 20%

o 2 Lab Tests (Week 13)

Word Processing – 5%

Spreadsheet – 5%

o 1 PowerPoint presentation (Week 12) – 10%

Exams – 60%

o The exam is a 100 marks paper over a duration of two hours.

For the presentation, Marks will be awarded on:

Simplicity and clarity of presentation

PowerPoint features used [Do NOT make excessive use of certain features]

Allocate 1 topic for groups of two students. Groups of 3 are prohibited

Please note that plagiarism is a severe offence. You should submit original assignments.

Deadline is generally week 12.

Oral presentation is not required.

You will get all the notes and exercises at:

http://vcampus.uom.ac.mu/CSE1010e

http://www.baycongroup.com/powerpoint2007/index.htm

http://www.baycongroup.com/wlesson0.htm

http://www.baycongroup.com/el0.htm

MODULE OBJECTIVES

On completing the Introduction to IT Module, you should be able

to:

o Use a personal computer comfortably and handle hardware

and software correctly.

o Understand the development of the computer from its

origins to the present.

o Distinguish between data and information and their roles in

modern computing.

o Associate the functions of the components of a computer

system with the descriptions of the components and compare

the capabilities of several computer systems.

o Use word processing, spreadsheets and presentation

graphics packages.

o Understand and apply the definitions of many of the

technical words used in the field of computers.

o Identify the types of data files, the methods of data

retrieval, and the methods of data modeling used in file

design.

o Perform the steps involved in basic systems analysis and

design.

o Appreciate the role of computer in society and the

workplace, and be aware of the future potential for, and

concerns about, the advancement of computer technology.

Chapter 1

Information Technology and Computers

Learning Objectives

Upon completion of this unit, you should be able to do the following:

1. Describe what Information Technology refers to.

2. Explain the relationship between Computers and Information Technology.

3. Outline various applications where computers are used.

4. Identify computers as consisting of both hardware and software.

5. Explain briefly what hardware and software are.

6. Differentiate among different types of computers.

7. Demonstrate basic understanding of computer networks.

8. Discuss the benefits and drawbacks of computers.

Overview

This chapter will give you an overview of the concepts underlying Information Technology (IT). It

starts by describing the increased importance of IT in our everyday life and provides a definition

for the term IT itself. It presents IT as consisting of computers supported by appropriate

connectivity through networking. A short description of hardware and software making the

components of computers is given as well as various types of computers are presented. The

student will also see various examples where computers are applied together with the numerous

benefits and drawbacks associated with their uses. Finally the chapter is closed with a brief note

on the trends affecting IT today after a quick overview of what networks and the Internet are all

about.

nformation Technology and Computers

1.0 Introduction During the past decade, Information Technology also known as IT has been of great interest to almost everyone. It has given rise to new and efficient means of manufacturing products in industries, innovative and fast ways of communication between people and provided various

benefits to every individual such that it is very useful to understand how it works. This chapter will

give an overview of what IT is all about as well as describe some common examples where IT is applied in our everyday life.

1.1 What is Information Technology all about?

In the Information Age that we live in, it is well known that good information helps an individual in

making the right decision at the right time. For instance, getting accurate information about

weather forecast helps airport operators to carefully plan the schedules for take-off and landing of

airplanes. In fact processing information to take actions or decisions is part of our everyday life.

You can yourself imagine the number of times per day this happens to you. Interestingly, human

nature seeks to make his life easier by finding new means of actually automating this task of

information processing; Information Technology does just that. Ranging from simple calculators to

complex mobile phones, IT has proved to facilitate the life of each and everyone by automatically

processing information and performing predefined tasks. However it is essential to note that the

success of IT lies mainly through the use of a common device that has been introduced in almost

every household today; that is the computer with the support of communication facilities

Figure 1-1 Computers and connectivity making IT

1.2 Computers at a glance Computers are electronic devices that are very good at processing information. There exist many kinds of computers to serve different purposes. Some examples include calculating product prices during checkouts in supermarkets, dispensing money at the ATM and controlling the running of modern cars. However all of them have got the following in common:

Hardware

Software

Hardware refers to the physical or tangible parts of the computer. They usually consist of input

devices to accept information to be processed, storage devices to store important information,

processing unit to process information and output devices to display/print processed information or

take necessary actions.

Figure 1-2 Components of a computer

Software on the other hand refers to programs (instructions) that tell the computer how to process

information to give the desired output. Two main types of software exist; Applications

Software and Systems Software. System software is made up of special programs that tell the

computer how to operate. An example is the Operating System such as Microsoft Windows that a

computer needs to operate whereas application software is any program that processes

information specific for the users need. Examples are word processing software, spreadsheet

software and payroll calculations software. Hence a computer requires both hardware (input,

storage and output devices) and software (system and application) in order to be able to serve the

purpose of a user.

Figure 1-3 Computers consist of both hardware and software

1.3 Types of computers Often when we hear of the term computer, the picture that comes to our mind is that of shown

in Figure 1-4 below.

Figure 1-4 Typical desktop Computers

But as mentioned earlier, this is one kind of computer that exists. In fact, there are various other

types that have been categorized as: supercomputers, mainframe computers, mini computers and

microcomputers. Their main difference lies in their processing capability, although size as well may

be another characterizing feature.

Supercomputers are the most powerful computers that exist. They have got very high processing power and are used by large organizations in advanced applications like space exploration.

Figure 1-5 Supercomputer at NASA

Mainframe computers have lesser processing power than supercomputers but they do provide great processing speeds and data storage. They are typically used for long periods

of time and mostly serve companies like international banks that have to process millions of transactions for their customers.

Figure 1-6 Mainframe computers

Mini computers are also known as midrange computers. They have got relatively high processing power and capacity that mostly fit the need for mid range organizations. They are used in manufacturing processes or handling email that are sent and received by a company.

Micro computers are the least powerful and the most commonly used are often referred to as Personal Computers (PC). They provide the necessary processing capability and

storage space that a common individual will require to perform routine tasks such as typing a letter, building a presentation, watching a movie etc. Desktop computers,

notebooks (laptops), Personal Digital Assistants (PDA’s) are all different categories of microcomputers.

(a)

(b)

Figure 1-7 Examples of Micro computers (a) PDA (b) Notebook

1.4 Applications of Computers Computers have introduced many interesting and practical ways of making our life easier. The examples listed below are only an indication of how useful they are but any other applications that

you may think of will surely make use of the power of computers.

Medical diagnosis and treatment are now extensively done using computers. Medical

doctors can now estimate the date of birth of babies and health status of babies during

pregnancy. Other examples include treating of cancer and brain scanning.

Manufacturing processes in industries now make use of robots that are controlled by

computers to build finished products from their raw materials with very little intervention

of human. Car manufacturers for instance make intensive use of robots.

Banking services like ATMs allow us to access our accounts 24 hours a day and 7 days a

week to perform routine actions like making a deposit, withdrawing money and verifying

accounts balance through mini statements. Additional services include mobile phones top

ups whereby prepaid mobile phone accounts can be automatically credited from a given

bank account.

Communication has never been easier than now by using mobile phones. Chat and

sending sms is now an integral part of our life. Modern mobile phones now enable viewing

the person to whom we are speaking with.

Entertainment such as IP television has made our life more interactive in that we can

select which TV program we want to view and at what time, process known as video on

demand.

Web based applications using the Internet has brought people even closer. New

businesses known as ecommerce have emerged such that a person can shop for almost

anything without having to leave his house. Online applications involving much less use of

paperwork such as booking for a flight, and seat reservation at the university avoids the

hassle of waiting in long queues and provide for a more efficient and quick means of

operation.

1.5 Computer networks and the Internet

Earlier we saw that IT consists of both computers and connectivity in order to bring about the

various benefits it provides. Connectivity in fact represents the possibility for communicating

between different computers. This process is achieved by networking (connecting) computers

together using connecting devices (cables and other specialized devices) and setting up of

strictprotocols (rules) for communication to take place. Computers that are connected together

form a network. There are different types of networks and the most common example is the one

you use to access the Internet. The latter in fact is a very large network and connects millions of

computers together.

Figure 1-8 Web page viewed on a browser with the help of Internet

A person will need a browser (E.g. Firefox, Microsoft Internet Explorer) to view web pages and a

modem to connect to the Internet. The term web and Internet are often used interchangeably. You

will learn more about the Internet and the Web in Chapter 10.

1.6 Benefits and drawbacks of IT So far, we have seen computers mostly as making our life easier. It is important however to recall

that any new technology if not well used can cause serious problems to people. Below is a list of benefits of using computers, followed by some computer drawbacks that should not be ignored. Benefits

Faster processing is achieved using computers compared to human beings especially when calculations are involved.

Storage facility allows individuals and especially organization to keep soft copies of their

work instead of hard copies like papers and large files that are cumbersome. This also

makes organization and retrieval of information easier and quicker. Hospitals using IT for instance can very easily have access to the file of any patient easily.

Many users can have access to the same service at the same time as in the case of a book that can be viewed at the same time by many students.

Professional services are delivered especially in advertising, video and image editing that gives a new dimension to the underlying industry.

Customizing outputs that allows you to write your own application software such that it suits your need better. An organization may wish to develop its own software that allows it

to calculate the salary of all its employees automatically and print out a summary after processing.

Integrated applications have been made possible with computers. For instance you can

watch movies, listen to music, type your report and talk over the Internet using computers.

Drawbacks

Loss of jobs has been very significant since the introduction of computers as many organizations have been able to perform the same tasks using lesser human intervention.

Security issues have been of great concern with IT. Many people have seen their bank

account manipulated, their privacy invaded and as well their businesses affected. This area

is often known as cyber crime.

Health problems resulting from excessive use of computers include eye strain, head ache,

back pain and others. Hence it is essential that special care is taken while using

computers.

Ethical issues such as illegal copying of other people’s works are now very easy using

computers. Other concerns include applying parental control to avoid that children are

exposed to adult materials over the Internet.

Software reliability mainly addresses the trust that people place in computer software. For instance, how far can we trust a lift that is controlled by a piece of software?

1.7 Trends in IT

An interesting feature of computers and IT is that the technology is ever changing. Computer

specialists are always finding new ways of improving our life and developing new computer

systems. Current trends aim at providing wireless services (without cables) to people while

improving on the speed and storage space of existing computer systems. Other trends include

reducing the size of computers, their costs and increasing their processing power while catering for

the various drawbacks mentioned earlier.

1.8 Further readings

O’Leary T, O’Leary L., “Computing Essentials”, complete edition, McGraw-Hill, 2004.

Capron H.L., Johnson J.A., “Computers, Tools for an information age” eighth edition, Prentice Hall, 2004.

Exercises

Multiple Choice Questions

1. Which of the following mostly describe what IT is about?

(a) Hardware and software

(b) Computers, communication devices and networks

(c) Application and System Software

(d) Different types of computers

(e) Software only

2. Computers are

(a) Special devices that store information

(b) Able to accept input data that need to be processed

(c) Process data to output desired information

(d) Of different sizes and processing power

(e) All of the above

3. _________ are instructions that tell the computer what to do.

(a) Documents

(b) Guidelines

(c) Software

(d) Information

(e) Procedures

4. _________ is the most powerful type of computer

(a) Mainframe

(b) Mini computer

(c) Micro computer

(d) Super computer

(e) Laptop

5. Which of the following is NOT an example of a micro computer?

(a) PDA

(b) Laptop

(c) PC

(d) Bank server

(e) Point of sale terminal

6. A _________ connects many computers together to allow sharing of information and

resources.

(a) Link

(b) Network

(c) Communication software only

(d) Cable

(e) Communication hardware only

7. Firefox is an example of a

(a) E-mail program

(b) Chat system

(c) Web page

(d) Voice mail

(e) Browser

8. The___________ is the largest network in the world

(a) Internet

(b) Web

(c) WWW

(d) World wide web

(e) All of the above

9. Protocols refer to

(a) Contracts between computer manufacturers and suppliers

(b) Set of rules for communication purpose

(c) Special type of network

(d) Software used in networks

(e) Agreements between different network providers

10. Cyber crimes are crimes

(a) Committed in cyber cafes

(b) That involve the use of computers

(c) Caused only by computer professionals

(d) Only committed by computer professionals

(e) That occur only in large organizations

Exercises Open-Ended questions

1. Using examples of your own, explain what IT is all about.

2. In your own words, explain how IT has changed the living standard of the common

people today.

3. Describe different types of computers stating specific situations where they are used.

4. IT is said to consist of both computers and networking facility. Explain this statement by

providing suitable examples.

5. Any new technology brings about threats. How far does this statement apply to IT?

6. What are hardware and software giving examples in each case?

7. The Internet is an example of a very large network. Explain this statement.

8. A server is a special type of computer that is used to provide services to other

computers. In which type of computer, does a server fall into? Suggest some examples of

servers.

9. List some major drawbacks IT and computers have brought about.

10. What are the trends that affect IT today?

Chapter 10

The Internet

Learning Objectives

Upon completion of this unit, you should be able to do the following:

1. Understand what is the Internet and how it works

2. Know what is the world wide web (WWW) and how it came about

3. Differentiate between the Internet and the WWW

4. Know what is a Uniform Resource Locator (URL)

5. Identify the various uses of the Internet

6. Understand what are search engines and how they are used

7. Know what are the different means of communicating on the Internet: email, blogs, wikis,

newsgroups, mailing lists, chat rooms.

8. Understand what are plug-ins and cookies

Overview

In this chapter, students are introduced to the various Internet and WWW concepts. The student learns about the Internet, its history, the WWW, the difference between the Internet and the

WWW and the various applications of the web. They will also be introduced to some new web concepts like wikis and blogs.

10.0 Introduction

In the last two decades, the Internet has known a huge growth around the world. Mauritius has

not been left behind - in 2004, there were some 77000 Internet subscribers in Mauritius (Mauritius

in figures, June 2005, CSO publication, page 23). With the advent of mobile technologies, the

Internet has known an even bigger growth. Nowadays people can connect to the Internet and send

emails using their mobile phones or some other mobile device.

10.1 What is the Internet? The Internet is a network of networks connecting all countries of the world. The networks are made of different kinds of computers which are connected to each other via cable, satellite or even using wireless technologies. These machines transmit huge amount of information between them. The Internet consists of:

many independent networks

computer hosts (servers)

routers & switches (hardware)

leased phone lines

satellite and radio connections

cable connections

wireless connections

10.2 History of the Internet

1960’s

The Internet started in the 1960’s when researchers were investigating the possibility of

connecting computers to share information and programs from anywhere. In 1969 the first such

physical network was developed by the ARPA (Advanced Research Projects Agency) which is now

known as DARPA (Defense Advanced Research Projects Agency). The network interconnected four

computers in four different universities in the United Stated and was known as the ARPAnet. In the

following years the ARPAnet grew as more computers and more networks were added to the initial

network.

1970’s

As the ARPANET grew, the need for a reliable service was felt and to cater for that a protocol was

required. The protocol would maintain effective communication between the different machines

and take care of problems like jamming, interference and loss of data.

In the early 1970’s a complete protocol called the Network Control Protocol (NCP) was developed

and users could now begin developing applications.

Web-based electronic mail was also developed. A few years later an improved protocol called

TCP/IP was developed, to allow computers and different kinds of network to communicate with

each other. In 1976 Europe joined the ARPANET. It was at that time that the term Internet was

introduced.

1980’s

In the 1980’s TCP/IP became ‘The’ protocol on the Internet. During the 1980s computer sellers

began to sell desktop computers equipped with networking software and companies started to

become interested with the Internet.

At the end of the 1980s, the first worm was released on the Internet causing concern on privacy

and security on the Internet. Terms like cracker and hacker were created.

1990’s

In the 1990’s the original ARPANET was dismantled and was replaced by the NSFNET backbone. At

that time the WWW was invented. The WWW changed the way information was presented and

accessed on the Internet. Web browsers were invented to access web pages. In 1997, all countries

of the world were connected to the Internet.

2000’s

In the 2000s there has been an explosion in the use of wireless devices such as mobile phones and

PDAs and therefore the WWW had to change to cater for these users as well. The web size

surpassed 1 billion indexable pages. (Survey carried out by NEC-RI and Inktomi)

10.3 The World Wide Web (WWW) The World Wide Web (also known as WWW or the web) is a series of web pages, connected to

each other via hyperlinks. Tim Berners-Lee invented the WWW in 1989 while working at CERN

research labs. He proposed a global hypertext project which would allow people to work together

by combining their knowledge in a web of hypertext documents.

Closely related to the WWW are the terms hypertext, hyperlinks and hypermedia. Hypertext is the

ability to have web pages containing links, which are text or buttons or graphics on a web page on

which you can click your mouse button to retrieve another document from the WWW into your

computer. This new document also contains further links that the user can click on, hence

navigating or browsing the WWW.

10.3.1 How does the WWW work? The World Wide Web is based on the client-server model. There is a web server and a client. In the client-server model, a client program makes a request to a server program which fulfils the request and sends a response. The server and client programs can be found on the same machine but most of the time they are found on two separate machines. A web server is a host computer with web server software installed on it and it stores and shares files over the Internet. Tim Berners-Lee wrote the both the first World Wide Web server, "httpd".

Examples of Web Server software are Apache and Microsoft IIS. A web client on the other hand is a computer with client software installed on it and it makes requests to the web server. Tim Berners-Lee wrote the first client, "WorldWideWeb" a what-you-see-is-what-you-get hypertext browser/editor. Examples of Web Client software are web browsers. A web site is a collection of web pages linked to each other via hyperlinks. Each website has a unique address that identifies it.

10.3.2 Uniform Resource Locator A Uniform Resource Locator (URL) is an address that identifies an individual file on the Internet. It is analogical to a phone number. Consider the URL below: http://www.uom.ac.mu/Faculties/foe/index.asp

http: The protocol

HTTP specifies the protocol that is being used. Examples of internet protocols are: HTTP for web

pages, FTP for files (movies, music files, programs) etc

www.uom.ac.mu: The domain name of the server

The Server is the computer where the website is hosted on the Internet.

Faculties/foe/: The path

The path is the folder or directory on the server in which the web page is found.

index.asp: The File

The File is the web page that the client is trying to access.

10.3.3 IP Address and Domain Names Every computer that is connected to the Internet must have a unique IP address (like a phone number) to identify it. An IP address consists of set of 4 numbers, each separated by a dot. Each number ranges from 0 to 255. Example of an IP address: 168.156.125.25

Web servers have a domain name as well as an IP address. Domain names are more easily remembered than IP addresses. A Domain Name Server keeps a list of Domain names and their corresponding IP addressees. Example of a domain name: www.uom.ac.mu

10.3.4 What happens when a person clicks on a link? Consider a person who comes across an interesting

link,http://www.uom.ac.mu/Faculties/foe/index.asp while surfing the web and clicks on it. The browser understands that this web page is being requested. It looks after the http:// and before the closing / if there is one. This represents the name of the server i.e the machine where the website resides and the specific page required. In the above example the server is: www.uom.ac.mu and the page is index.asp.

The browser sends the request to that server and the request travels the Internet moving from machine to machine until it reaches the server. When the server receives the request, it looks at file extension of the requested file to determine what kind of file it is. Some files can be sent directly while others need to be processed first and then sent, hence the need to look at the file extension.

The server then sends a response to the client; the response travels the Internet from machine to machine until it reaches the client. When the client browser receives the response, it reads the data and renders it in the browser for the user. The whole process is a series of requests and responses. The new document contains hyperlinks and the user can again click on these, starting the whole process again.

10.4 Difference between the Internet and the WWW

The Internet or the net is a network of networks. As mentioned previously it is made from

computers and cables. The main purpose of the Internet is to share information. When you are

sending information to someone else on the Internet, that information is broken down into packets

and the address of the receiver is attached to the packet. This is then sent to the next computer

connected to the Internet which sends it to the next computer and so on until it reaches the

destination computer. Therefore the Internet delivers packets anywhere in the world and normally

well under a second.

The World Wide Web is an abstract space of information. It consists of all the web pages

connected to each other via hyperlinks. On the Internet there are computers – hardware; on the

web there are text documents, images, music, videos and other files - information. On the Internet

the computers are connected via cables while on the web the documents are connected via links.

The Internet came about much earlier than the web and exists without it. The web is based on the

Internet and cannot exist without it.

10.5 Internet protocols There are different kinds of computers on the Internet and these computers have different operating systems e.g. Windows, UNIX, Mac OS, etc. For these machines to be able to communicate they need to follow the same rules and these are defined by protocols. A protocol is the special set of rules that different communicating bodies use to exchange messages. These rules define how information is sent and also what happens in case there is loss

of information during the transfer. The most common protocols that are used on the Internet are HTTP, FTP, TCP/IP, HTTPs…

10.5.1 TCP/IP (Transmission Control Protocol/Internet Protocol) TCP/IP is the basic communication language of the Internet. As mentioned in the history section, it followed the original protocol on the Internet, NCP. It is also used in private networks like intranets and extranets.

10.5.2 HTTP (Hypertext Transfer Protocol) HTTP is the set of rules used to transfer information and files on the WWW. The files can be text, graphic images, sound, video and other multimedia files.

10.5.3 HTTPs (Hypertext Transfer Protocol) When a URL starts with HTTPs, it means that HTTP itself is to be used, but with a different default port and an additional encryption/authentication layer between HTTP and TCP. This is a more

secure version of HTTP and is indicated by a URL starting with HTTPs and a padlock in the status bar.

10.5.4 FTP (File Transfer Protocol) FTP is a protocol that is used to exchange files on the Internet.

10.6 Accessing the Internet

For a home user to have access to the Internet, the following components are normally needed:

A PC A modem A telephone line or a wireless device An Internet Service Provider (ISP)

The Internet Service Provider, also called Internet Access Provider, is an organization that offers users access to the Internet and to its related services like email. Many ISPs are telephone companies but not all of them. The user connects to the ISP which is always connected to the Internet and can thus access the Internet.

A software

The user also needs some software to connect to the Internet. These can either be web browsers or email clients.

10.7 Web Browsers

A web browser is a software application that enables a user to view and interact with text, images,

and other information located on a web page at a website on the World Wide Web. Examples of

web browsers are Internet Explorer, Netscape Navigator, Mozilla Firefox, Opera and Apple Safari.

Although browsers are typically used to access the World Wide Web, they can also be used to

access information provided by web servers in private networks or content in file systems.

10.8 Search Engines and Web Directories The WWW contains billions of files loaded with information. If a user is looking for some specific information, it is very difficult to start unless he has the address of a website that he has obtained somewhere.

A special kind of website exists to enable users to look for information. Such websites are known as search engines. Search engines enable Internet users to search for web pages containing specific information. They also have the option of refining the search by putting conditions such

that more specific and appropriate information is obtained.

There are various kinds of search engines; some can be used to look for any kind of information

while some can only be used to look for information on a specific subject. There are general search engines, meta search engines, regional search engines, pay-per-click search engines, email-based search engines, answer-based search engines, job search engines, shopping search engines, blog

search engines, news search engines, multimedia search engines, medical search engines and a lot more. Closely related to search engines are web directories. Web directories are human-compiled indexes of sites, which are then categorised. The fact that a website is reviewed by an editor before being placed in the index means that getting listed in a directory is often quite difficult. Consequently, having a listing in a directory guarantees the website a good amount of well-targeted visitors. Most search engines will rank a website higher if they find that web site in one of the directories.

Popular Search Engines: Popular Web Directories

Google –

http://www.google.com

Yahoo –

http://www.yahoo.com

Lycos –

http://www.lycos.com

Open Directory Project -

http://dmoz.org/

Ask Jeeves –

http://www.askjeeves.com

Looksmart -

http://search.looksmart.com/

While web directories are maintained by human editors, search engines operate on their own.

10.9 Uses of the Internet 10.9.1 Information

The Internet was created initially to share information and programs and it is still very much used

today as a source of information. This has increased even more so with the advent of the WWW

since information is presented better and it is easier to use search engines to look for information.

People can use the Internet to search for almost any kind of information. Someone interested in

gardening can visit millions of websites related to gardening on the Internet. Someone else who is

interested in cooking can use the WWW to look for recipes or can learn to cook. There is

information for everyone on the Internet, whatever the person’s age and interests.

Most major newspapers and news channels are also online these days. Therefore anyone who

wants to know the latest news simply has to visit any one of these websites and since these are

updated many times a day, they are even more up-to-date than newspapers.

10.9.2 Communication One of the major uses of the Internet today is for communication purposes. It is much faster to send an email to someone than to send a letter and the response can be as rapid. There are various means of communication on the Internet. [See Section 10.10 for more information on

communicating on the Internet] Communication can also be in terms of sharing information. As mentioned previously, most major newspapers and news channels are online these days and news are communicated in real time (as they happen).

10.9.3 Education More and more the Internet is being used for education purposes. Students use the Internet to look for information when they have some coursework or assignment to submit or they use it as a

learning aide.

But many people are also following courses online, meaning they register for a course and instead of going to a classroom at a university or training centre, they sit in front of a computer at home

or at the office and follow their courses by reading the lecture notes online or by viewing a video of their lecturer delivering a course. This mode of learning known as e-learning has the added advantage of taking place at home or at the office and at a time that is convenient to the learner.

10.9.4 Business More and more businesses are going online either for marketing purposes or for conducting business directly. Ecommerce and eBusiness are two terms that almost everyone has heard of.

Electronic business, or "e-business", is any business process that is empowered by information technology.

Electronic commerce, e-commerce or ecommerce consists primarily of the distributing, buying, selling, marketing, and servicing of products or services over electronic systems such as the Internet and other computer networks.

EBusiness is more than just e-commerce. It covers business processes along the whole value chain: electronic purchasing ("e-procurement") and supply chain management, processing orders electronically, customer service and cooperation with business partners.

10.9.5 Entertainment A lot of people use the Internet for entertainment purposes. People listen to music and watch movies on the Internet – they can either do these in real time (e.g.http://www.bbc.co.uk/radio/) or they can download them and use later. People also play games on the Internet

(e.g. http://games.yahoo.com/games/front), either alone or with other people who are connected to the Internet.

10.10 Communicating on the Internet

10.10.1 Email 10.10.1.1 What is Email?

Electronic mail, abbreviated e-mail or email, is a method of composing, sending, and receiving

messages over electronic communication systems. The electronic communication system can be

either over the Internet or can be in an intranet.

The term e-mail applies both to the Internet e-mail system based on the Simple Mail Transfer

Protocol (SMTP) and to intranet systems allowing users within one company or organization to

send messages to each other.

Intranet email predates the Internet. Email came into existence in 1965 as a way for multiple

users to communicate. But the invention of the Internet brought about web based email.

Electronic mail can be used to:

Send a single message to many recipients

Send a message that has attachments, these include text, audio, video, graphics or some

other documents like a PowerPoint presentation

Send a message to which a computer program responds

Email addresses have a specific format. They are made of two parts separated by the “at” sign

character, @. The prefix of the email address identifies the user and the suffix gives the domain

name of the mail server.

For example: Cse1010user@uom.ac.mu

The domain name uom.ac.mu indicates that “uom“ is an academic institution, “ac“ sub domain,

found under Mauritius “mu“ domain.

10.10.1.2 Privacy Issues of Email Email messages are not private. Sometimes email messages are not encrypted when they are sent over the web and therefore can be read by other people. Email messages go through a series of machines before reaching the recipient and these emails can be easily intercepted and read.

Furthermore, many ISPs keep a copy of email messages on their mail servers before sending them to the user and although the user might have deleted his email after reading it, a copy of the email may still be on the mail server for some time.

10.10.1.3 What is Spam?

Email spam is the sending of unsolicited identical email messages to thousands (or millions) of

recipients. Spammers (perpetrators of spamming) harvest these email addresses from web pages

where they are listed or obtain them from databases. Therefore WWW users should be careful

when they are asked to provide their email addresses, these addresses can be harvested by

special software on the web and the user can be spammed as a result.

Spammers send emails for various reasons. Emails are sent first and foremost for advertising

purposes. Spamming is a very cheap mode of advertisement; thousands of emails can be sent in

one click. Email users often get more spam emails than unsolicited emails. The user either has to

waste time reading each one of them and ensuring they are spam emails before deleting them

hence wasting a lot of time. Else these get accumulated over time and take up a significant

amount of disk space. Disk space is not an issue for email users who use free web emails but for

companies that provide email to their employees, it can be a real problem.

Spam emails can also be sent as fraudulent emails asking for personal information or can even

contain viruses. These two cases are more dangerous than the previous one and unfortunately

very much exist. People can be sent fraudulent emails from their bank and they might reply, the

spammers thus get their bank details and these can be used fraudulently.

10.10.2 Chat Rooms

Chat is another popular activity on the web. A chat system is one where the user has to register and is provided with a username and password. Using this username and password he can access the chat system at any time of the day. Different kinds of chat system exist; in some chat systems the user has a ‘buddy list’ and he usually chats to these people only, other chat systems are more open and the user can choose to chat to anyone randomly.

Figure 11-1 Example of chat: msn messenger

Examples of chat are MSN Messenger, Google Talk and Skype.

Chat rooms can also be 2D visual chat rooms. In these chat rooms the user can see a graphic representation of other members and they can move about in the “room”. Examples of this type of

chat room are The Palace and The Manor. There are also 3D chat rooms. These are similar to the 2D chat rooms except that they are in 3D and are more realistic. Examples of this type of chat are There, Second Life, andActiveworlds. All these chat rooms also have audio and video communication so that the users can either hear each other or even see each other.

10.10.3 Newsgroups

A newsgroup is a repository for messages posted by many different users from around the world.

Newsgroups are arranged in hierarchies making it easier to find specific information. Usually

newsgroups focus on a specific subject.

10.10.4 Mailing Lists A mailing list is a collection of names and addresses used by an individual or an organization to send material to multiple recipients simultaneously. The term is often extended to include people subscribed to such a list, so the group of subscribers are referred to as "the mailing list", or simply

"the list". A user who wants to have his name added to a public mailing list must send an email request to the administrator of that mailing list.

10.10.5 Forums Forums are websites on the WWW where discussions can take place. Forums are also known as web forums, message boards, discussion boards, discussion forums, discussion groups, bulletin

boards or forums. The difference between forums and newsgroups is that some additional software is required to participate in a newsgroup, a newsreader while there is no need for additional

software to participate in a forum.

10.10.6 eNewsletters A newsletter is a regularly distributed publication generally about one main topic that is of interest to its subscribers. When the newsletters are sent by email, they are called eNewsletters. eNewsletters can be published by businesses, especially companies, or clubs to provide information of interest to their employees or members. Most newsletters are free although some are fee-paying. eNewsletters are similar to Mailing Lists except that they are more commercial in nature.

10.10.7 Blogs A blog (the shorthand for weblog or web log) is a website where messages are posted and are displayed in reverse chronological order. A blog is usually on a specific topic e.g. politics, health, games or can be a personal diary. A blog is different from newsgroups and forums since only the author or authoring group can

create a topic for discussion on the blog. There are cases where blogs function as forums when other people are granted access to post on the blog but the blog owners can initiate and frame the

discussions. Example of a blog creating website is: http://www.blogger.com/ Example of a blog is: http://cse1010.blogspot.com/

A blog is very easy to create. The user usually does not need to know any web design or

programming. The user simply uses a blog creating website to create his blog. He first registers

with the website, then he specifies the name of his blog and finally he chooses a template for his

website. The blog website takes care of creating a blog for the user in the format selected. Even

adding content to the blog is very easy, the user has to login and then can add content through a

simple user interface. Once again the blog website takes cares of updating the user’s blog.

Figure 11-2 Example of a blog: http://cse1010.blogger.com

10.10.8 Wikis

A wiki is a special kind of website where the user can add, remove and edit the content as well as

simply visiting the website. Some wikis allow users to modify the website directly while others

require prior registration of the user.

Wikis usually contain a system which records all changes made to items so that the page content

can be reverted back if need be.

Examples of wikis are:

http://www.wikipedia.com

http://www.wikiindex.com/Wiki_Index

Figure 11-3 Example of a wiki: http://www.wikipedia.com

10.10.9 Plug-ins A plug-in is a small computer program that understands how to interpret one specific data format.

The plug-in usually interacts with a specific program to provide a certain, usually very specific,

function.

When a new data format is invented, the plug-in to handle the format must also be developed. For

example, the plug-in for an audio clip must be able to use audio hardware to convert the digitized

format into sounds. Before the new format can be used, the plug-in must be downloaded and used

as an extension to the browser. Most new browsers have the some commonly used plug-ins.

Typical examples are plug-ins to display specific graphic formats (e.g. SVG, Scalable Vector

Graphics, if the program does not support this format natively), to play multimedia files, to

encrypt/decrypt email (e.g. PGP, Pretty Good Privacy), or to filter images in graphic programs.

Examples of plug-ins are Flash player and QuickTime.

10.10.10 Cookies A cookie is some information that has been sent from the server of a website to the browser. Each

time the user accesses that web site, it communicates the cookie information to the server. This helps the web server to recognize the user. Cookies are used for authentication purposes, to track users, to keep information on user preferences and information on users when they are shopping online. A Cookie is not a program but simply some data and therefore cannot perform any operations. Hence it is virus-free.

10.11 Further readings

Internet Society Website, http://www.isoc.org World Wide Web Consortium Website, http://www.w3.org

Wikipedia, http://www.wikipedia.com

Blogger Website, http://www.blogger.com/

Tim Berners-Lee and Mark Fischetti, Weaving the web, 1999

Exercises Multiple Choice Questions

1. Which of the following is NOT required when connecting to the Internet?

(a) A pc

(b) A web browser

(c) A telephone line

(d) A modem

(e) A printer

2. What does a URL do?

(a) Stores video clips

(b) Identifies the location of an electronic file

(c) Prevents viruses from spreading

(d) Transmits live web cam pictures

(e) Creates backup of data

3. What is a hyperlink?

(a) A type of error message

(b) A video game

(c) A very fast internet connection

(d) Words or pictures that when clicked on redirect you to another page

(e) A type of network connection

4. Which of the following is NOT a possible error message when accessing a website?

(a) The page does not exist

(b) The URL typed is wrong

(c) You do not have authorization to view such a page

(d) The site is having technical problems

(e) Your modem cannot be detected

5. Spam is

(a) Sending unsolicited messages

(b) Sending emails to friends

(c) Deleting an email on reception

(d) A web browser

(e) A web server

6. Mozilla Firefox is an example of:

(a) A web browser

(b) A web server

(c) A software to listen to music

(d) A software to watch video

(e) A word-processing software

7. A Blog is

(a) A personal web site where other people can leave comments

(b) A special kind search engine

(c) A web browser

(d) A web server

(e) A website that can be edited by anyone

8. A wiki is

(a) A personal web site where other people can leave comments

(b) A web browser

(c) A web server

(d) A website that can be edited by anyone

(e) A router

9. A protocol is

(a) A mode of transmission on the web

(b) A set of rules that communicating bodies follow to communicate

(c) A special kind of search engine

(d) A website that can be edited by anyone

(e) A kind of network

10. A web server is

(a) A computer which contains server software and which hosts web pages on the web

(b) A special software that is used to access web pages on the web

(c) A special software that is used to read emails on the web

(d) A kind of virus that spreads when a user requests a web page

(e) Another name for a web browser

Open-Ended Questions

1. What are the main differences between the Internet and the WWW?

2. How would you subscribe to a mailing list?

3. What does a user need to start using the Internet at home?

4. What is the purpose of a search engine?

5. What are blogs and wikis?

6. What are protocols? Why are they needed on the Internet?

7. What is the difference between a newsgroup and a forum?

8. What is an IP address? Why are computers assigned IP addresses on the web?

9. Explain the term Domain name and its importance on the web.

10. When do you need to install a plug-in and why?

Chapter 11

Computer

Security

Learning Objectives Upon completion of this unit, you should be able to do the following: 1. Understand the meaning and objectives of computer security

2. Define basic terminology associated with computer security 3. Describe the types of computer attacks, viruses and misuse of computer systems 4. Identify various security issues associated with email 5. Explain why encryption is important

6. Discuss the importance of passwords to control access 7. Evaluate and select appropriate techniques to secure a computer system 8. Appreciate the need of regulations and laws for security in IT.

Overview This chapter presents the basic concepts of computer security.

The objective of computer security is to protect a computer system’s valuable resources, such as

information, hardware, and software. Security relies on confidentiality, integrity, and authorisation

or availability.

Nowadays, as computers become ever-more prevalent and connected with each other, computer

systems need to be protected against increasing number of attacks, malicious codes and IT

misuse. Several techniques are available to minimise computer security risks, namely passwords,

encryption, firewalls and antivirus software.

Furthermore, computer users need to be aware of various security threats and the tools available

to protect computer systems. Up-to-date legislation governing computer security, data protection,

privacy laws and other IT laws are vital in order to fight against cyber offences and protect users.

11.0 Introduction Over the last decades, computing environment has changed from unconnected or standalone

computers to a highly interconnected network of powerful computer systems. Many traditional activities have been extended or even transferred to the computing environment. For example, instead of sending a letter, we send email, in addition to going to the bookstore, we can buy a book online, instead of buying the newspaper, we visit a news Web site, instead of visiting a bank, we go to the bank’s Web site, and instead of keeping accounts information in a book, specialised

software are used. With our increased daily dependence on computers and networks at home or in office, ensuring that computer systems are secure has become very important.

11.1 What is computer security? The meaning of the term computer security has evolved in recent years. Traditionally, most people’s idea of computer security focused on the physical computer. An example is the prevention of theft or damage to the hardware. Today, however, with omnipresent computer access, communications, and networking, physical measures rarely provide meaningful protection for either the information or the service. Generally, computer security is referred as the process of preventing and detecting unauthorised use of computer systems and the data stored on them.

Prevention measures help to stop unauthorised users (also known as "intruders") from accessing any part of the computer system. Detection helps to determine whether or not someone attempted to break into the system, if they were successful, and what they may have done.

11.2 General concepts Security is frequently associated with some core areas, which are the aims of computer security. The security aims are discussed below.

11.2.1 Confidentiality Sensitive data transferred over computer network need to be protected. Confidentiality means to

protect the data being transferred from exposure to third party. The need for keeping information secret arises from the use of computers in sensitive fields such as government and industry. Encryption is one of the methods used to avoid data from being “seen” during transmission. Data are encrypted before sending and decrypted on receiving.

11.2.2 Integrity Integrity of data is important for data transmitted over computer network. It guarantees the data or information being transferred is intact and trustworthy. In other words, the data received by the

intended receiver should be exactly the same as it was sent. Digitally signed document helps to maintain the integrity of data or information being transmitted.

11.2.3 Authorisation and Availability Authorisation is the access control that authorise who has the right to access what information or operation in a system. It can be controlled on individual or group basis. Users are given different access privilege or rights to perform task in a computer system. Usually, access is granted by entering valid user name and password. For example, students may not be able to access certain intranet services, while their lecturers have access rights to them.

The availability of computer systems is crucial to many businesses or organisations and in some

cases the lack of availability can result in significant financial losses. For example, the

unavailability of banking computer systems can result in clients unable to access their funds or in

the bank employees unable to process transactions.

11.3 Computer Security Threats

The act of deliberately accessing computer systems and networks without authorisation is generally referred to as hacking. Computer security threats differ in importance. The types of attacks or misuse of computer systems can be placed in the following general categories:

11.3.1 Denial of Service (DoS) A “denial of service” (DoS) attack, is an attack against a system, e.g. Web site, that either reduces

its performance or overloads it to the extent that the system hosting it crashes. The detail description of how the DoS attack occurs is beyond the scope of this chapter. However, a "denial-of-service" attack is characterised by an explicit attempt by attackers to prevent legitimate users of a service from using that service. Examples include:

attempts to "flood" a network, thereby preventing legitimate network traffic.

attempts to disrupt connections between two machines, thereby preventing access to a

service. attempts to prevent a particular individual from accessing a service.

· attempts to disrupt service to a specific system or person. Many well-known e-commerce and news web sites have experienced the DoS attack.

11.3.2 Masquerading or Spoofing Masquerading or spoofing, is an impersonation or imitation of one entity by another for both deception and usurpation. When the attacker is capable of sending data with the illusion that it is

coming from a different source, this is called spoofing. It lures a victim into believing that, the entity with which she is communicating, is a different entity. For example, if a user tries to log into a computer across the Internet but instead reaches another computer that claims to be the desired one, the user has been spoofed. Email spoofing is where you send an email message with a From address different than your own.

11.3.3 Virus or Malicious code Malicious codes are mischievous programs, the purpose of which is to disrupt the normal operation of computer systems. They spread by ‘infecting’ other computers in many ways through floppy or portable disks, CD-ROMS, emails and file downloads.

Types of malicious codes Worms are usually small programs which are capable of copying themselves between systems. They often overwhelm network and systems resources as they attempt to spread.

Viruses are similar to worms except that they attach themselves to other pieces of code and are

spread as that code is executed.

A Trojan is a piece of code which looks like a desirable application while performing malicious

activity in the background. An example of this would be a pirated video game, which functions

correctly and allow users to play while installing an unauthorised program to the operating system.

The lifecycle of computer viruses The life cycle of most computer virus has four stages:

i. In the dormant phase, the virus is idle, but not all viruses have this stage.

ii. In Propagation phase, the virus places an identical copy of itself into other programs or into

certain system areas.

iii. Triggering phase is when the virus is activated to perform the function for which it was created.

iv. In the Execution phase, the function for which the virus was created, is performed. The function

may be harmless or damaging.

Virus types The following are three main categories of viruses:

i. Transient (parasitic) virus: It is the most common virus form. It attaches itself to a file and

replicates when the infected program is executed.

ii. Memory resident virus: This virus type is lodged in main memory as part of a system program.

Virus may infect every program that executes.

iii. Boot Sector Viruses: It infects important files located in boot sector and spreads when the

computer system is switched on. Consequently, it gains control of computer systems before the

virus detection tools, thus it is very hard to notice. Common carrier files for boot sector viruses are

AUTOEXEC.BAT, CONFIG.SYS, IO.SYS, .COM files and .EXE files.

Most antivirus software functions with the following approach:

First there is detection to determine the files infected and the location of the virus.

Secondly identification is used to spot and classify the specific virus.

Then removal process eliminates the virus from all infected systems, so the virus cannot

spread further.

Finally, recovery is done to restore the computer system to its original state.

11.3.4 Theft and Sabotage Theft of confidential information or software is a potential problem. It consists also of sabotaging

information systems by damaging computerised data. Theft and sabotage also occurs from unauthorised access or trespassing into a computer system.

11.3.5 Fraud Computer fraud is a serious cybercrime nowadays. Examples are, changing input data in an illegal way or entering unauthorised data and modifying output of a computer system. Other types of IT-related fraud are: financial fraud by misuse of stolen credit card details or other financial information, telecommunication fraud by the use of telecommunications systems or services for dishonest or fraudulent purposes.

According to surveys, the most common type of attacks are those resulting from malicious codes (i.e. computer viruses types). The Internet and Information and Communication Technologies have

increased security threats. Example, prior to an attack, hackers break into computer workstations and servers with high speed Internet commections and install hard-to-detect malicious software. At the designated time, a signal is sent via the Internet to these computers to launch hidden programs, causing the targeted or ‘victim’ site to be flooded or jammed with requests. This can lead to access denial or disable Internet-based services of the victim server.

11.4 Security of email transmissions Email is one of the most popular application on the Internet. Approximately more than 15 millions e-mails were sent each day in 2004 and therefore it is easy to see that e-mails need to have

security. Viruses started as simple self-replicating programs that spread via the transfer of floppy disks, but e-mail gave virus files a passport to travel. Hence, computer viruses have achieved record-breaking infection rates. Because the email permits users to attach files to e-mail

messages, viruses can travel by e-mail from one network to another, anywhere on the Internet. Email system is therefore a point of vulnerability that is exploited to invade any system and network. It is estimated that over 70% of today’s business email is spam. Email spams are

unsolicited commercial e-mails sent to many users. Spam is considered as a prominent source of various types of malicious code.

Email security is a service that intercepts and examines the email addresses to a domain. Any

suspicious origin of email is filtered before reaching the mail server. This prevents malicious

attachments, spams, other unwanted mail and attacks off the network. Spam blocker or anti-spam

software are used to provide email security.

11.4.1 Encryption Emails travel through many different computers on the way to their destinations, and anyone with access to those computers has the ability to read the emails. Email encryption is commonly used

to convert an email message into an unintelligible form that prevents people other than the intended recepient from reading it. This is a powerful tool to protect user privacy.

The science of encrypting information is known as cryptography. Encryption is the process of

coding a message so that its meaning is concealed. The process of transforming an encrypted

message back into the original readable form is called decryption. Usually, the encryption

algorithm, or also called cipher, is made up of mathematical steps for encrypting and decrypting

information. A special piece of secret data, called a key, is normally used in both the encryption

and decryption process.

Figure 11-1 A simple encryption model.

The famous Caesar’s cipher is a classic encryption example and it was used for concealing meaning

of messages by Julius Caesar. This simple algorithm specifies that alphabets in a message can be

replaced by offsetting each either to the right (forward) or to the left (backward), and the key

specifies how many letters the offset should be. Example:

If the original message or plaintext is “MEET ME AFTER THE BATTLE”, and suppose Caesar’s

encryption procedure is to offset 3 alphabets to the right. Value 3 is normally the secret key only

known by sender and receiver. The cipher operates by replacing each letter by another letter, a

fixed distance away. Therefore, the computed encrypted message is “PHHW PH DIWHU WKH

EDWWH”.

When information is to be transmitted somewhere, encryption is used so that if the information is

intercepted before reaching its destination, the interceptor will not be able to interpret its real

meaning. Encryption is also applied to sensistive information that are stored on a database. Banks

and other financial institutions conducting their business over open networks, such as the Internet,

use very strong cryptography systems to provide security and trust as well.

11.5 Enable e-mail client protection Most e-mail clients, such as Microsoft outlook, come with features that can help to protect against

malicious attachments entering or leaving the computer system. Some built-in protection features in Microsoft Outlook are:

Attachment security – Outlook defines two attachment security levels: level 1 and level 2. Level

1 attachments include extensions such as .vbs, .exe, and .com, which are automatically blocked by

default. Level 2 attachments include all other types such as .doc, .xls, and .ppt. Level 2

attachments are not blocked by Outlook; however a dialog box prompts the user to save the

attachments to the hard disk when accessing it. The pupose of the dialog box is to give the user

an opportunity to scan the file before opening it.

Install Antivirus software - An anti-virus software consists of computer programs that attempt

to identify, thwart and eliminate known computer viruses and other malicious software (also called

malware). If a piece of code or program in a file matches any virus identified by the anti-virus

software during a virus scan process, then one of the following actions can take place:

Attempt to repair the file by removing the virus itself from the file.

Quarantine the file, such that it remains inaccessible to other programs and its virus can

no longer spread.

Delete the infected file.

Some common anti-virus software packages are: Norton Anti-Virus, McAfee VirusScan and PC-

cillin. Regular updates of the anti-virus software are needed to ensure consistent protection

against new viruses.

11.6 Web security

The usefulness of the World Wide Web is due, not just to browsers, but also the web components

that enable services for end users through their browser interfaces. These web components use a

wide range of protocols and services to deliver the desired content to end users. Many web

security concerns have arisen, and they can be grouped in three main tasks:

Securing a server that delivers content to users over the Web.

Securing the transport of information between users and servers over the Web.

Securing the user’s computer from attack over a web connection.

Security has become a problem for all those who use the web, whether home users or large

companies connecting to the Internet. Hackers, computer viruses and other threats are constantly

affecting web services.

11.6.1 Firewalls

One of the most popular security component used on computer systems connected to the Internet

is the firewall. In building construction, a firewall is designed to keep a fire from spreading from

one part of the building to another. Similarly, in networks and computer systems, a firewall is an

important security component. A firewall is a combination of hardware components and

appropriate software that controls or filters access between two networks. It is considered as a

first line of defence in protecting private information and it is placed at the junction point between

the two networks, as shown in Figure 11-2 . Encryption helps to solve many security problems.

However, it is not a complete solution and is often complimented with a firewall to restrict the

types of access permitted between a computer or private network and the rest of the Internet (i.e.

a firewall protects against unwanted Internet traffic). The main component of a firewall is a packet

filter, which is capable of preventing data packets of a certain type from passing through the

firewall.

Figure 11-2 Network with Firewall

11.7 The role of people in security The heart of any security system is people. This is particularly true in computer security, which deals mainly with technological controls that can usually be bypassed by human intervention. For example, a computer system authenticates a user by asking that user for a secret code; if the correct secret code is supplied, the computer assumes that the user is authorised to use the

system. If an authorised user tells another person his secret code, the unauthorised user can masquerade as the authorised user with significantly less likelihood of detection.

In computer security, social engineering is a term that describes a non-technical kind of intrusion.

It relies mainly on human interaction. It often involves tricking other people to break normal

security procedures. For example, a person using social engineering to break into a computer

network would try to gain the confidence of someone who is authorised to access the network in

order to get them to reveal information, such as username and password, that compromises the

network’s security. Prevention includes educating people about the value of information and

increasing people’s awareness about security threats.

The current environment in which we live and operate in, people use computers for everything,

from banking and investing to shopping and communicating. Therefore, a “culture of security” is

needed so as to protect all computer users from security breaches. People are considered the

weakest link in the security chain. Awareness of the risks and available safeguards is the first line

of defense for security of computer systems.

11.8 Passwords A password is a secret combination of different characters (letters, numbers or symbols) that is used to allow only authorised users have access to certain services, e.g. email account, or files on

a computer. Password selection is one of those critical activities that is often neglected as part of a good security baseline. Many computer systems today are only protected by a simple user ID and password. If an attacker guesses the right userID and password combination, then, all other steps taken to secure the computer system collapse. Therefore selecting a ‘good’ password is critical to protecting computer systems.

There are mainly two types of passwords: weak and strong passwords.

A strong password is one that is designed to be hard for a person or program to discover. It is

sufficiently long, random by the user who chose it, so that “guessing” for it will require a long

time. Examples of strong passwords: J*p2zeO4!F or #79kLLwyee. Strong passwords are normally

at least eight characters long with a mix of character types, do not contain user name or other real

name and they do not contain a complete dictionary word.

A weak password is one that is short or is a default, or which can be rapidly guessed by searching

a subset of all possible passwords such as words in the dictionary, proper names, words based on

the user name or common variations on these themes. Example of weak passwords: admin, 4321

or test.

Weak passwords provide attackers with easy access to computers or networks, while strong

passwords are considerably harder to crack.

The following guidelines help to make a password more difficult to guess or obtain:

Should be at least eight characters long

Should have at least three of the following four elements

o One or more uppercase letters (A – Z) - One or more lowercase letters (a – z) - One or more numerals (0 – 9)

- One or more special characters or punctuation marks (!@#%*& . , ; ?)

Should not consist of dictionary words

Should never be the same as the user’s login name or contain the login name.

Should not consist of the user’s first or last name, family member’s name, birth dates, pet

names, or any other item that is identified with the user.

Given enough time and computing power, virtually any password can be cracked by simply testing

all possible passwords. It is therefore necessary to have users change their passwords on a regular

basis. For example, users have to change their passwords every 60 to 90 days, very secure

computer systems may need passwords change every 30 to 45 days. Additionally, passwords

should not be reused, i.e. using the same password later on.

11.9 Techniques for securing computer systems In order to ensure a stronger computer security against hackers, viruses and other threats, the following general steps may be adopted:

1. Many free utilities, such as file sharing software or toolbars and other pieces of software of

unknown origin, come loaded with adware and spyware. Suspicious or untrusted software should

not be downloaded or installed, as they can affect computer performance.

2. Antivirus software can quickly detect when viruses, worms, and other types of malicious code

are introduced to any computer. It is essential that current version of supported antivirus software

is installed and set for regular and automatic updates.

3. Computer users have to assign strong password to prevent hackers from stealing confidential

information. Hard-to-guess passwords that can withstand automated password cracking attempts

is important for higher security.

4. The computer system’s firewall provides an additional level of protection against malicious

activity by examining and restricting network traffic to the computer.

5. Strong encryption provide secrecy during data communication or storage.

6. Backup is a way of securing information; it is another copy of all important computer files kept

in another location. These files are kept on hard disks, CD-Rs, CD-RWs, and tapes. Backups act as

an insurance copy in case of data loss.

7. In the case of operating systems and other softwares, patches have an important role of fixing

security holes. A patch is a small piece of software designed to update and fix problems with a

computer program. To facilitate updates, operating systems often provide automatic update

facilities.

11.10 Security and law Due to increasing vulnerability of individuals regarding their privacy and protection of data, there

have been significant regulatory activities on the issue of data protection and confidentiality. All individuals have important confidentiality needs that are usually associated with the right to privacy. In the case of organisations, the need for confidentiality is of such importance to protect

information assets, intellectual property rights or professional duties. The laws in this area are quite diverse as the level of security required varies for different circumstances and applications.

To develop Mauritius as a cyber island and strengthen the ICT sector, legal frameworks have been

put in place to promote the growth of ICT industry. The four main IT related laws currently

existing in Mauritius in 2006 are outlined below:

Data Protection Bill 2004

The objective of this Bill is to provide for the protection of the privacy rights of individuals in view

of the developments in the techniques used to capture, transmit, manipulate, record or store data

relating to individuals. Privacy laws refer to the rights of individuals or organizations to restrict the

use of data.

Computer Misuse and Cybercrime Act 2003

In Mauritius, the Computer Misuse and Cybercrime Act 2003 had been introduced for legal

protection against hackers and regulating criminal behaviour in the IT world.

This Act was enacted to provide for repression of criminal activities perpetrated through computer

systems. This legislation is used to protect the society from cyber crimes and to give a strong

signal to would-be perpetrators. Cyber criminals face severe penalties if found guilty within this

law. Three common cyber crimes, namely financial crimes, illegal interception of computer services

and child pornography on the Web have been made criminal offences under the Computer Misuse

and Cybercrime Act.

The Electronic Transactions Act 2000

It provides the appropriate legal framework to facilitate electronic transactions and

communications and give a new orientation to the traditional way of doing business by fostering

the conduct of transactions by electronic means. It also provides for the legal recognition and

regulation of electronic records, electronic signatures and their security.

The Copyright Act 1997

It was introduced in July 1997 to provide the appropriate legal framework for the protection of

intellectual property rights, including software and electronic databases.

This law has paved the way for major information technology companies such as Microsoft to set

up a regional office in Mauritius.

11.11 Examples of Computer Viruses In this section, a few well-known computer viruses that have affected computers worldwide are presented.

i. The Melissa Virus (March, 1999)

Melissa is the best known of early viruses that attach themselves to Microsoft word documents. It

infected about a million computers, congested network traffic and caused problems for email

servers worldwide. If the user opens the file containing the Melissa virus, it infects the current

computer and also sends itself to the first 50 addresses in the individual’s email address book.

ii. The Love Letter Worm (May, 2000)

Also known as the “ILOVEYOU” virus, the worm was spread over an estimated 45 million

computers via e-mail attachments with the email subject line of “ILOVEYOU”. When the user ran

the attachment, it searched the system for files with specific extensions in order to replace them

with copies of itself. It also sent itself to everyone in the user’s address book. Again, since the

receiver generally knew the sender, most individuals opened the attachment without questioning.

iii. The Code Red Worm (July, 2001)

The worm took advantage of vulnerability of early version of Microsoft’s IIS web servers.

Thousands of computers connected to the Internet were infected within hours of release. Microsoft

released a patch for the vulnerability. The patch should be installed and the system rebooted

before being connected to the Internet.

iv. The Slammer Worm (January, 2003)

The virus exploited initial vulnerability in computers running Microsoft’s SQL server. Later,

Microsoft released a patch for the vulnerability. But the worm infected a large number of

computers within the first 24 hours of release, caused network outages and other IT related

disruptions. Once a machine was infected, the host would start randomly selecting targets and

sending packets to them to attempt infection.

Exercises

Multiple Choice Questions 1. Protecting data being transferred from exposure to third party is referred as

(a) denial of service

(b) integrity

(c) authentication

(d) unavailability

(e) confidentiality

2. When the attacker is capable of sending data with the illusion that it is coming from a different

source, this is called :

(a) fraud

(b) spoofing

(c) redirecting

(d) sabotage

(e) spamming

3. Which of the following is not considered good practise for password security?

(a) Changing the password on a regular basis

(b) Using a combination of upper- and lower-case characters, a number, and a special character in

the password

(c) Avoiding inclusion of dictionary words

(d) Not writing the password down

(e) Using less than eight characters long

4. A combination of hardware components and appropriate software that controls or filters access

between two networks is called:

(a) an antivirus

(b) a firewall

(c) a port

(d) a trojan

(e) a network card

5. A piece of code which looks like a useful application while performing malicious activity in the

background is:

(a) a trojan

(b) a worm

(c) a cypher

(d) a patch

(e) a bug

6. The act of manipulating legitimate users to obtain confidential information is called:

(a) masquerading

(b) Intruding

(c) social engineering

(d) fraud

(e) malware

7. Which of the following is not a carrier file for boot sector viruses?

(a) .EXE file

(b) .COM file

(c) .XLS file

(d) .BAT file

(e) .SYS file

8. Which legislation has been specifically enacted to protect the society from criminal activities

perpetrated through computer systems?

(a) The Electronic Transaction Act 2000

(b) The Copyright Act 1997

(c) Data Protection Bill

(d) Computer Misuse and Cybercrime Act 2003

(e) Criminal Code Act

9. The method used for converting a message into an uninteligible form to avoid being “seen”

during transmission is:

(a) filtering

(b) shielding

(c) encryption

(d) protection

(e) integrity

10. What are the three main goals of computer security?

(a) Control, intelligence, action

(b) Central intelligence agency

(c) Confidentiality, integrity, availability

(d) Confidence, integrity, action

(e) Confidentiality, intelligence, availability

Exercises

Open-Ended Questions

1. What are the three main objectives of computer security?

2. Explain why social engineering is such a successful form of attack?

3. Describe the function of firewall in computer security?

4. Explain how encryption can provide secure email transmission? Use Caesar’s cipher with key

value 4 to encrypt the message “I came I saw and I conquered”.

5. Distinguish between strong and weak passwords, and outline the characteristics that make a

password difficult to guess.

6. Describe the types of attacks that e-commerce web sites frequently experience.

7. Write a brief essay outlining the steps required to minimize the possibility of an attack on a

computer system.

8. Define the term computer worm, and distinguish it from computer virus.

9. Describe some of the user security responsibilities that you feel are most important for users to

remember.

10. In an environment familiar to you (the university or where you work, for example) determine

what computer security measures are employed. Discuss whether you think they are sufficient.

Chapter 12

Software Utilities

Learning Objectives Upon completion of this unit, you should be able to do the following: 1. Differentiate between Shareware and Freeware.

2. Understand the concepts and importance of compressing data.

3. Be aware of the importance of keeping systems free from adware and spywares. 4. Understand the usefulness of download managers.

5. Understand the importance of Antivirus software and keep the system virus free. 6. Have knowledge of:

a. Taking backups of data. b. Synchronize the files between their systems and external storage devices. c. Burning Data onto CDs and DVDs.

d. Using various types of media players.

Overview This chapter introduces the students to a wide range of software utilities, which will help them to ensure that the data is properly taken care of. This chapter assumes that the student is familiar with the terms like virus, security, encryption and Internet. The students are expected to go through the chapters on Computer Networks, Computer Security and The Internet before proceeding with the current chapter. The student will understand the importance of antivirus

software, keeping the computer free from adwares and spywares, data compression, data backup. The student is also made aware of the usefulness of file synchronization between the computer and external storage devices so as to maintain consistency of the data files. The various tools

available to burn data be it normal data or audio or video data on to CDs and DVDs will also be highlighted. The chapter also highlights to students the popular products available in the current scenario to enable them to carry out the various tasks mentioned.

12.0 Introduction Software utilities are programs that are developed to provide useful service by performing common and housekeeping tasks for the computer.

12.1 Categories of Software The various categories of software that are available on the Internet are:–

Public Domain Software – Software can be classified as public domain software if it is

not copyrighted and is free for use without any restriction. The authors of this category of

software place them in the public domain in order to share them with other users.

Freeware – Software can be classified as freeware if the author has control on it. The

author defines the terms of usage and distribution of the software. Under normal terms,

the author of the software allows the users to use it for personal use and does not permit

the user to use it for commercial purpose. The user is legally bound to abide by the terms

of usage set by the author. A freeware is available to the users and is cost free. The users

must not expect any help in terms of support if there are errors in the software. Most of

the freeware softwares include information of how a user can use the software. Usually

most of the freeware softwares do not have a time limit. Freeware that requires the users

to send a postcard to the author are termed as Postcardware. The idea behind this is to

humanize the transaction so as to remind the author that there are users making use of

his software. Some freeware softwares are also termed as Donationware where payment

for the software is completely optional.

Shareware – Software can be classified as shareware if it released by the author for the

users to try it before making a decision to purchase the software. Sharewares are

copyrighted. The duration for trying the software varies from author to author. After the

expiry of the trial period, the user is expected to either register the software by paying the

author for further usage or discontinue the usage by uninstalling the software. Usually

most of the authors release the shareware versions of the softwares in a manner such that

after the expiry of trial period, either the software stops running or important features of

the software get disabled. By registering the software, the user can avail service

assistance and software updates. Shareware softwares where some features are limited till

the user registers the software are termed as Crippleware. Shareware softwares where a

popup screen continuously prompts the user to register the software are termed

as Nagware.

Malware – Malware is a type of program usually known as malicious softwares which gets

installed on the user’s computer without the knowledge of the user through the web

browser and collects the user’s information (passwords, IP address, Operating System

details etc..) and transmits the information to a third party, usually a hacker.

Adwares belong to the category of programs which are legally allowed and are usually

associated with programs not registered by the users. Usually the programs are sponsored

shareware or freeware. When the programs are being used, a small portion of the screen

is utilized for displaying advertisement banners or pop up windows and this is a possible

source of revenue for the authors of the programs. When the programs are terminated,

the advertisement banners disappear. Adware can be either malicious* or non malicious.

*Malicious code is a portion of code designed in order to intentionally cause damage or change the

way of working of the system.

Figure 12-1 Example of an Adware on an application

When the adware assumes a high degree of intrusive nature, by tracking the surfing behavior of

the user in order to serve advertisement purposes then it is termed as a spyware. Thus spyware

is a malicious program which is installed by the user unknowingly along with a freeware or a

shareware which was downloaded from the Internet. Once the spyware is installed on the

computer, it monitors the user’s activity and transmits the information to a third party without the

user’s knowledge. The type of information that can be transmitted by a Spyware ranges from

gathering information about e-mail addresses, passwords to credit card numbers. The spywares

have the capability of monitoring the keystrokes of the users, gather information about other

applications, make provision for installation of other spywares, scan the data on the computer and

access cookies amongst others.

12.2 System Utilities The software programs which help in keeping the state of the computer system healthy are known as system utilities. Some of the essential system utilities are

Disk Defragmenter – As the user stores files on the hard drive, the storage methodology

may or may not be sequential. In due course of time, the file needs to be split into several

portions and stored in several locations on the hard drive according to the availability of

space. If a file is split into several portions then the time taken to read the file is longer

when compared to reading the file which is stored at contiguous locations. In order to

overcome this problem, the Disk Defragmenter arranges all the portions of the file in a

manner that they are all in a contiguous location so that it improves the file access time.

Thus a Disk Defragmenter is a computer program which is designed to increase the speed

of reading the file and the amount of usable space by rearranging the files and unused

space. Most of the Disk Defragmenters are included along with the Operating Systems like

Microsoft Windows (Figure12-2), utility packages like Norton Utilities

(www.symantec.com), or other standalone defragmenters like PerfectDisk

(www.raxco.com/products/) or Diskeeper (www.diskeeper.com).

Figure 12-2 Microsoft Windows Disk Defragmenter Utility

Disk Cleanup – In due course of time, there are a lot of unnecessary files stored on the

hard drive which might not be of any use and take up a lot of storage space. Disk Cleanup

is a system utility which is used to delete temporary and other files that are no longer

needed. Disk Cleanup searches the hard drive, and then lists temporary files, Internet

cache files, and unnecessary program files that can be deleted safely. Most of the

Operating Systems have this utility inbuilt.

Figure 12-3 Microsoft Windows Disk Cleanup Utility

Data Backup and Restoration – The process of copying files from the computer onto a

second medium such as zip drive, pen drive or tape drive is termed as data backup. This

helps the user to safeguard the data and retrieve it in case of loss of data. The traditional

data backup medium used with Personal Computers was floppy disks. But considering the

nature and amount of data being dealt with in the current scenario, the floppy disks have

become obselete due to limitations with respect to the medium. They have been replaced

with technologies such as CD-RWs, Pen drives, DVD-RWs and online

backups. Pen drives are also known as key drives. These drives can hold huge

amounts of data. There are a lot of softwares which not only take care of backing

up the data but also synchronising the data both at the source and destination

drive. Some of the backup and synchronisation utilities are

Allway Sync (Figure 12-4) (http://allwaysync.com/), Good Sync

(http://www.softpedia.com/get/System/Back-Up-and-Recovery/GoodSync.shtml), Memeo

(http://www.memeo.com/) and others. Some Operating Systems provide inbuilt data

backup and restoration utilities like windows has a data backup utility (Figure 12-5).

Figure 12-4 Allway Sync - Data Syncronisation

Figure 12-5 Microsoft Windows Data Backup Utility

12.3 Data Compression Utilities

When there is a need to transfer files from one location to another location, quite often it is found

that the size of the file is large thereby making the movement of the file between the locations

very slow. Very often the files are graphic and multimedia files. Thus data compression means

storing the data in a format that requires less space than the usual space. Data compression is

widely used in backup utilities, spreadsheet applications and database applications.

Compression tools are used which reduce the size of the file as well as the time taken to transfer

the file. Compressed files are commonly referred to as zipped files.

Groups of files can also be compressed into a single compressed file. This compressed file is

commonly referred to as an archive file. By doing so the user has the advantage of being able to

download / upload several files as a single compressed file and making use of the disk space

efficiently.

In order to reduce the size of the file the compression tools use complex mathematical algorithms

to search for repeating patterns and replace them with smaller codes which reduce the overall size

of the file. By doing so, the overall number of bits and bytes in a file are reduced. There is a large

range of data compression techniques of which only few are standardized.

To view the contents of a compressed file, corresponding decompression tools are used. These

tools read the codes and convert them back to original patterns thereby expanding the file back to

the original size.

Most of the currents tools have the options for both compressing and decompressing the files. The

most common compressed files have the extension .zip, .tar, .sit, .rar and .cab. Some of the

common compression / decompression utilities are Winzip (www.winzip.com) (Figure 12-6),

WinRAR / RAR (www.rarlab.com) (Figure 12-7), PKzip / PKunzip, StuffIt (http://www.stuffit.com)

amongst others.

Figure 12-6 Screenshot of WinZip

Figure 12-7 Screenshot of WinRar

It is also possible to create archive files with .sea or .exe extensions which are self-extracting files.

These do not need any additional software to decompress them. These files can be opened like an

ordinary file and the file gets automatically launched. Thus these compression utilities allow huge

files, be it data or pictures or video into archive files which utilize less disk space and thereby

making the process of transmitting between locations an easy job.

12.4 Download Utilities

As seen in Section 12.3, it is possible to compress files into smaller sizes in order to allow easy

transmission between different locations. However this set up may not be appropriate when the

files are to be downloaded from the Internet. Whenever there are disruptions in the Internet

connection, there is no flexibility in terms of continuing with the download of the file. When the

files are to be downloaded, many browsers allow a certain number of files to be downloaded

simultaneously.

Thus some of the drawbacks that arise when the files are downloaded via the traditional browsers

are as follows

Inability to pause the download of a file.

Inability to download several files simultaneously from a site.

Inability to download the file at a faster rate.

Inability to resume paused/broken downloads.

The need for a program which handles efficient downloading of files from the Internet arose due to

the above mentioned drawbacks. Most of the download managers integrate seamlessly into the

web browsers. Most of the current web browsers have their own Download Managers. Apart from

utilities for downloading files there are also utilities for downloading whole sites and updating them

regularly.

Users who use dialup connections are the ones who benefit a lot from Download Managers. The

Download Managers give the flexibility of scheduling downloads and hanging up the Internet connection after completion of download. They also keep track of all the links the user clicks. They

also allow the user to place several files in queue for download.

Some of the software companies provide their own downloaders (Figure 12-8) to download software from their own sites to exercise control over the redistribution of their software.

Figure 12-8 Examples download utilities provided by software companies

Some of the commonly used utilities for downloads are

DownloadStudio (www.conceiva.com/products/downloadstudio/) (Figure 12-9)

Download Accelerator (www.speedbit.com/) (Figure12-10)

Internet Download Manager (www.internetdownloadmanager.com)

Internet Download Accelerator (www.westbyte.com)

Fresh Download (www.freshdevices.com)

GetRight® (www.getright.com)

Figure 12-9 Screenshot of Download Studio

Due to the rapid advances in technology, the Download Managers have assumed capabilities

beyond the basic download feature. Some of the additional features are

Files are scanned as soon as the files are downloaded (The files will be scanned only if there is an antivirus application installed in the computer).

Files can be downloaded from several mirror sites (servers) simultaneously to reduce the download time drastically.

They allow the users to have a preview of the multimedia files as they are downloaded.

Figure 12-10 Screenshot of Download Accelerator

12.5 Antivirus Softwares

As seen in Chapter 11 Section 11.3.3, it is necessary for users to protect their computers from

various types of viruses which are released every now and then. The category of software whose

primary objective is to protect the computer from virus attacks is known as antivirus. Antivirus

software searches the storage devices of the computer for any known and potential viruses and

removes any that are found. Due to the rapid growth of the Internet, it has become necessary for

each and every user to safeguard his/her computer from virus attacks. Most of the antivirus

softwares include auto update feature which automatically downloads the profiles of new viruses

on to the computer from the company’s website. Most of the antivirus companies release the

updates weekly or upon the discovery of new potentially destructive viruses. Some of the

companies also have virus removal tools specific to a particular virus.

Antivirus software can be installed like any other program and executed. They can also be

configured to perform automatic scans of the computer by specifying the schedules and

automatically download latest virus definitions. Whenever a virus is discovered, the antivirus

specialists try to analyse the virus by isolating it. By doing so, they get a better understanding

about the effects of the virus and devise a strategy of detecting the virus and removing it.

When an antivirus program is run, it checks the computer, it compares the contents of each file

with the virus definitions it has and if a match occurs, it tries to remove the virus. If the antivirus

program cannot clean the file, it quarantines the file so that the virus does not infect other files in

the computer. Every month a large number of viruses are released into the network and it very

important for the antivirus program to have the latest virus definitions. Some of well known

antivirus software are: Norton Antivirus (www.symantec.com) (Figure12-11), McAfee

(www.mcafee.com) amongst others.

Figure 12-11 Screenshot of Norton Antivirus from Symantec

12.6 Anti–Spyware Utilities

As seen in Section 12.1, programs that help the user to protect his/her computer against

spywares are termed as anti-spywares. Usually most of the anti-virus companies bundle anti-

spyware program along with the anti-virus software. Some of the anti-spyware programs are

WinPatrol (www.winpatrol.com), Windows Defender

(www.microsoft.com/athome/security/spyware/software/default.mspx) (Figure 12-12), Spybot

(http://spybot.safer-networking.de/) (Figure 12-3) amongst others.

Figure 12-12 Windows Defender from Microsoft

Figure 12-13 Spybot from Microsoft

12.7 Multimedia Utilities

Multimedia Utilities are programs which help the user to record and play audio-video clips, burn

CDs and DVDs, manipulate pictures amongst others. Many of the multimedia utilities have the

capabilities of managing (conversion/editing) media (audio/video) files, burning them on to the

storage media (CD-ROMs/DVDs). Some utilities include an additional capability of taking data

backup and retrieving media data from the discs. Therefore it is quite difficult to categorize the

utilities as either Audio-Video Utilities or CD-ROM/DVD Burner Utilities or Image Editing Utilities.

Some of the commonly used multimedia utilities are:

Windows Media Player (http://windowsmedia.com/download/download.asp) – The users

can play streamed media content from one easy-to-use application. The Media Player

supports streamed media file types including WAV, AVI, QuickTime, and RealAudio and

RealVideo. Apart from playing media files (Figure 12-14), Windows Media Player has the

capability of constructing play lists and saving them (Figure 12-15) or burning them on to

a CD-ROM (Figure 12-16).

Figure 12-14 Microsoft Media Player – Playing Music Files

Figure 12-15 Microsoft Media Player – Creating Play Lists

Figure 12-16 Microsoft Media Player – Burning Music Files

Roxio DigitalMedia SE (Figure 12-17) – This program is exclusively available on Sony computers. The features of this program are

o Audio — Enables the user to create an audio CD which includes CD audio burning for CD

player use, Jukebox CD burning for PC use, and MP3 ripping from CDs.

o Backup — Enables the user to take backups of the CDs/DVDs or the entire storage

media.

o Copy — Enables the user to copy a disc, write images on discs, and store images on

your hard disk.

o Tools — Enables the user to delete data and check the finalised disc.

Figure 12-17 Screenshot of Roxio Digital Media SE

QuickTime Player (www.apple.com/quicktime/download/) – QuickTime is the Apple

technology that supports streaming video, sound, music, 3D and virtual reality. QuickTime

VR (Virtual Reality) allows the user to rotate objects, zoom in or out, look in any direction,

and navigate from one scene to another.

RealOne Player (www.real.com/player/index.html) – The RealOne Player streaming

media system delivers rich media experiences to World Wide Web users through the

synchronization and playback of multiple media types. It also supports CD and DVD

burning .

The NERO 6 Ultra Edition (www.nero.com/nero7/eng/index.html) – The salient features of this application are:

o CD and DVD burning

o DVD-Video Photo, Data and Audio Backup o applications to edit audio, mix multiple audio tracks, watch VCD, SVCD and DVD movies o Play media files.

Figure 12-18 Screenshot of Nero 6 Ultra

12.8 Further readings

http://www.pcworld.com/downloads/

http://www.download.com/

Exercises

Multiple choice questions

1. Which of the following statements are true with respect to freeware:

I. The author defines the terms of usage and distribution of the software.

II. It can be used for commercial purpose.

III. The user is legally bound to abide by the terms of usage set by the author.

IV. Support is provided by the author if there are errors in the software.

(a) I & II Only

(b) II & III Only

(c) III & IV Only

(d) I & III Only

(e) II & IV Only

2. Which of the following statements are true with respect to shareware:

I. They are released by the author for the users to try it before making a decision on the

purchasing the software.

II. They are copyrighted.

III. They continue to function after the expiry of the trial period.

(a) I Only

(b) II Only

(c) III Only

(d) I, II & III

(e) None

3. Shareware softwares where some features are limited till the user registers the software are

termed as ______________.

(a) Crippleware

(b) Nagware

(c) Spyware

(d) Adware

(e) Malware

4. ________________ is a type of program which gets installed on the user’s computer without

the user’s knowledge and transmits the user’s information to a third party.

(a) Postcardware

(b) Crippleware

(c) Nagware

(d) Adware

(e) Malware

5. ________________ Utility takes care of arranging all the portions of the file in a manner that

they are all in contiguous locations.

(a) Disk Cleanup

(b) Disk Backup

(c) Data Compression

(d) Multimedia

(e) Disk Defragmenter

6. Which of the following statements are true with respect to Data Compression Utility:

I. Makes use of mathematical algorithms to search for repeating patterns and replace them with

smaller codes which reduce the overall size of the file.

II. Enables transfer of large files from one location to another by compressing the size of the file.

III. For every Data Compression Utility there exists a corresponding Decompression Utility.

IV. Data Compression Utility does not allow the creation of self extracting compressed files.

(a) I, II & III Only

(b) I, III & IV Only

(c) II, III & IV Only

(d) I , III & IV Only

(e) I, II & IV Only

7. Which of the following statements are true with respect to Disk Cleanup Utility:

I. It is used to compress all large files into smaller files.

II. Scans the hard drive for the files that can be safely deleted.

III. Deletes the temporary files and other files that are not needed.

(a) I & II Only

(b) II & III Only

(c) I & III Only

(d) I only

(e) III Only

8. Which of the following statements are true with respect to download utility?

I. Allows the user to pause the download of a file.

II. Allows the user to download several files simultaneously from a site.

III. Allows the user to compress the file at the site and download it to their computer

(a) I Only

(b) II Only

(c) III Only

(d) I & II Only

(e) II & III Only

9. Which of the following statements are true with respect to Antivirus software?

I. Takes care of performing automatic scans of the computer

II. Cleaning the infected file on detection

III. Quarantines an infected file

IV. Preventing infected programs from getting installed on the computer.

(a) I,II & III

(b) II, III & IV

(c) I , III & IV

(d) I, II & IV

(e) None

10. Which one of the following is not a CD burning utility?

(a) Real One Player (b) Nero 6 Ultra Edition (c) Quick Time Player (d) Roxio Digital Media SE (e) Windows Media Player

Chapter 13

Issues and Trends in IT

Learning Objectives Upon completion of this unit, you should be able to do the following:

List and describe health related issues to IT.

Demonstrate an understanding of ergonomics and recommendations for a computer user.

List and describe several ways that IT can be misused.

Explain the need for a legal framework resulting from the use of IT.

Discuss concerns related to copyright and IT.

Describe what ethics in computing relate to.

List and describe some of the major trends in IT.

Overview

This chapter highlights the issues and trends in IT. The first part of the chapter discusses the

health, legal and ethical issues that are associated with the use of IT or more specifically

computers at home, in the workplace or in a public area. It provides examples of health problems

that can occur with the use of computers while providing for precautions to avoid these problems.

The chapter also introduces the concept of ergonomics as an efficient way to use computers in a

healthy and productive manner. IT being a tool can also be misused and so various examples of

how IT can be misused are given to create an awareness of the risks that computer users are

exposed to. An overview of the legal framework to protect any individual involved in computers is

also provided with special attention given to the laws that exist in Mauritius. A brief introduction of

copyright is given since it is very easy to breach such rights using computers. Ethics as a

complement to existing IT laws are presented so as to ensure correct use of IT and computers as a

technology. The second part of this chapter deals with the new trends in IT such as wearable

computers, Biometrics and IP Television to name a few.

13.0 Introduction

Information technology is associated with numerous benefits that have indeed enhanced our living

standards. Unfortunately as mentioned earlier in Chapter 1, any new technology if not well

utilized may cause serious problems and information technology or more specifically computers are not to be excluded from this category. This chapter will give an overview of the health, legal

and ethical issues that need to be catered for with the use of computers. Various examples of how

an individual’s health can be affected when using a computer are described followed by the precautions that are required to avoid such problems. IT use is regulated by certain laws, hence common misuses of IT and a brief description of IT

related laws in Mauritius are given. Copyright, an important issue in relation to computers, is then presented. Some ethical guidelines as to the proper use of IT are provided. Finally the new trends in IT today are introduced.

13.1 Health issues

Computers have become a common tool in the workplace, at home and even in schools today. Many people use computers for different tasks and recently it has been observed that people spend more and more time working on computers. Unfortunately, this has given rise to many side effects, especially in the workplace where the health of many people has been affected. It is therefore essential to know how to make healthy use of computers in order to avoid such

problems. The following sections describe different health issues that need special attention when using computers.

13.1.1 Physical health concerns

If a person sits for long periods of time in an uncomfortable position while typing and lookingat a

computer screen, the following physical problems may arise:

Eyestrain and headache

Fixing a glared screen for long periods of time and at a short distance eventually causes fatigue on our eyes. If not taken care of, this can result in eye strain problems and headache. Recommendations include:

1. Taking a short fifteen minutes break for every hour. 2. Use a good screen that does not flicker and is not blurred. 3. Ensure that any light source is not reflected on the computer screen and if

possible use anti glare shields. 4. Always use computers in a well lit room and keep the screen at a reasonable distance form you.

(a) (b)

Figure 13-1 (a) Eyestrain resulting from prolonged exposure to computer

screen (b) Headache due to excessive working on computers

Repetitive strain injury (RSI)

This is the name given to a number of injuries that occurs especially in people who are

involved in heavy repetitive work such that additional strain is imposed on their neck,

fingers, hands, wrists and arms resulting in serious pains to different body parts that need

medical care. Carpal tunnel syndrome is one type of RSI that affects mostly people who

use keyboards extensively with the result that the tendons and nerves in their hands are

damaged. In some cases, the affected people cannot even open doors or shake hands and

sometimes need to undergo surgery to solve the problem. Such situations can be avoided

by taking frequent breaks while working and using ergonomickeyboards

(see section13.1.2).

(a) (b)

Figure 13-2 (a) Arm and wrist pain due to improper positioning when working

on computers (b) Carpal tunnel syndrome causing pain in the wrist

Back and neck pain

Monitors, tables, chairs and documents being worked on are often placed at improper positions while working on computers. Consequently many people suffer from back and

neck pain. Fortunately many manufacturers are now providing specially designed computer chairs and tables that can be adjusted to the height and comfort of the computer user to avoid such problems. Also computers monitors should be adjusted so that they are at or slightly below eye level and document holders should be adjustable. Footrest as well is recommended to prevent leg fatigue.

(a) (b)

Figure 13-3 (a) Neck pain resulting from improper position when working on

computers (b) Back pain can result when working for long hours and using

uncomfortable chair

13.1.2 Ergonomics

Ergonomics in simple terms studies factors that relate humans to the things they use with the aim

of designing devices, or methods of working that can be fitted to human abilities instead of doing

the reverse. In this way, it is expected that users will not suffer from health risks while at the

same time maintaining productivity. Considering the use of computers in the workplace or at

home, ergonomics will provide recommendations as to the specifications of the chair, table,

computer screen, position, height and seating arrangement required in order to cater for the

health of the user. Figure 13.4 shows such a typical ergonomic arrangement.

Figure 13-4 Ergonomics applied to computer user

13.2 IT and the Law

During recent years, IT has been at the heart of many disputes whereby people have faced many

situations resulting from the misuse of such technology. Some examples include:

Illegal copying and distribution of software such as Microsoft office suite.

Intrusion into organizations’ computers to steal confidential information such as customer

profiles.

Sending of unsolicited emails (spam) to potential buyers.

Sending of infected files/viruses over networks.

Illegal transfer of funds.

Monitoring networks to steal confidential information such as credit card numbers and

passwords.

Blocking or stopping a service such as an online store like amazon.com or a bank ATM’s

network.

Consequently there has been an urgent need to define a proper legal framework to protect every

individual either directly or indirectly related to IT. The framework consists of carefully defined laws that govern proper use of IT to protect the rights of an individual or an organization. Actually different laws exist for different countries and Mauritius has its own IT related laws. Refer to Chapter 11; Section 11.10 for a few examples of IT related laws in Mauritius.

13.2.1 Copyrights ©

Computers have made it easy to copy and edit materials like music, movies, images and

documents that are easily available over networks like the Internet and from secondary storage

devices like CDs. Distributing these materials is much easier now and often most of them are

copyrighted, meaning that only the authors have the right to use, modify or distribute them.

Hence any other individual that copies, modifies or distributes a copyrighted material will be

infringing the right of the legitimate author and can be pursued by law. Hence you must seek the

permission of the author before using a copyrighted material.

To know whether a material is copyrighted and hence protected under the copyright law, an

individual needs to look for the symbol ©, that should appear somewhere on the material

concerned. Exceptions to the use, modification and distribution of copyrighted materials do exist

however and these are:

For research and private study

For criticism and review

13.3 Ethics in computing Ethics govern the moral conduct of an individual. It allows a person to distinguish between

what is right to do and what he/she has the right to do. This is particularly important in

specialized areas like in medicine. In that case, a doctor should always follow good ethical

practices like keeping confidential all medical history of a patient if the latter wishes so.

Similarly a people dealing with computers need to follow certain rules that govern their

behaviour when using IT. For instance as a university lab computer user, you may have

the right to delete the assignment of someone from one of the computers in order to clear

hard disk space, but is it ethical to do so? Should you not speak to the person who has

written the assignment first? What if it was your assignment and someone else deleted it?

And take for instance, the lab technician; what if he purposely allows someone to print a

large number of pages while preventing you from printing a single page for no obvious

reason. This is really unfair you would say. In practice there are various situations where

people dealing with computers tend to abuse technology and unfortunately the law does

not make any provision for such acts mostly because it is very difficult to impose such

laws. Considering the assignment example, the student has the total freedom of deleting

the file since it is a computer that any student should be able to use at their convenience.

Does that mean the student who saved his work on that computer is to be blamed?

Obviously no, since he/she has also the right to save any work on the computer

concerned. Eventually as you can see, there is confusion as to what kind of law to

generate and hence ethics as a moral guiding principle is essential here. That is why some

professional organizations like the Association of Computing Machinery (ACM), British

Computer Society (BCS) and the Institute of Electronic and Electrical Engineers (IEEE)

have come up with strict guidelines that give instructions as to how computer professionals

and users should be making use of IT. Figures 13.5 – 13.7provide a highlight of the

guidelines provided by ACM, IEEE and BCS.

Figure 13-5 Highlights of guidelines for ethical behaviour provided by ACM

Figure 13-6 Highlights of guidelines for ethical behaviour provided by IEEE

Figure 13-7 Highlights of guidelines for ethical behaviour provided by BCS

In addition to these guidelines, the Computer Ethics Institute, comprising of members

of the IT professions like IBM and the academic, corporate and public policy communities

developed a set of general guidelines known as the “Ten Commandments of Computer

Ethics” for the proper use of Information Technology.

The recommendations put forward are as follows:

1. Thou Shalt Not Use A Computer To Harm Other People.

2. Thou Shalt Not Interfere With Other People’s Computer Work.

3. Thou Shalt Not Snoop Around In Other People’s Computer Files.

4. Thou Shalt Not Use A Computer To Steal.

5. Thou Shalt Not Use A Computer To Bear False Witness.

6. Thou Shalt Not Copy Or Use Proprietary Software For Which You have Not Paid.

7. Thou Shalt Not Use Other People’s Computer Resources Without Authorization

Or Proper Compensation.

8. Thou Shalt Not Appropriate Other People’s Intellectual Output.

9. Thou Shalt Think About The Social Consequences Of The Program You Are

Writing Or The System You Are Designing.

10. Thou Shalt Always Use A Computer In Ways That Insure Consideration And

Respect For Your Fellow Humans.

However it is important to note that ethics complement the law and hence we need both in

order to provide for a secure environment whereby people use Information Technology for

the benefits of human beings.

13.4 Trends in IT

Currently there is an ever increasing range of applications that make IT more useful. Traditionally

the use of computers was primarily for basic data processing. But with advancements in both

processing power and size of computers, the range of applications expanded from word

processing, data storage and spreadsheet applications to a wider range of innovative and useful

applications. These applications include educational software, desktop publishing, computer-aided

design and manufacturing (CAD/CAM), games, modelling and simulation, networking and

communications software, electronic mail, the World Wide Web, digital imaging and photography,

audio and video applications, electronic commerce applications, groupware, file sharing, search

engines, and many others. The growth and diversity of applications greatly increase the utility of

IT, leading to its further expansion. This chapter highlights some of the innovative applications

that have made a mark in the current decade and will be used for quite some time. The trend in IT

is becoming increasingly interdisciplinary in nature. One of the major progresses is wearable

technology which is the basis for all future applications. Grid Computing is also making rapid

strides. These two technologies form the basis of a wide range of IT applications.

13.5 Wearable Technology

Wearable technology has been in existence for quite some time now. It broadly refers to mobile

electronic devices that can be discreetly implanted into the user’s outfit as part of the clothing or

as an accessory which is operational and can be accessed with minimum hindrance to the user’s

normal activity. The basic aim of using a wearable device is to enhance the user’s activity and

environment in an invisible mode. The most important trait of these devices is that they are

context sensitive in nature. By context sensitivity, it is meant that the devices must be able to

recognize the change in the user’s state and environment. The driving force behind the wearable

technology is the ever increasing desire for hands free computing.

Wearable technologies can range from micro sensors which are built into clothes, watches,

jewellery to computers which are integrated as a part of the user’s accessory. These can be used

in several domains and namely health related application domain and smart clothing.

New smart textile and clothing systems are being developed by integrating sensors in the textile

constructions. Application fields for these value-added products are protective clothing for extreme

environments, garments for the health care sector, technical textiles, sport and leisure wears.

Wearable Technology is proving to be useful in improving the quality and reducing the cost of

caring for the aging population, in particular, health monitoring, mobile treatment and nursing.

They are mainly used for monitoring patients over extended periods of time. Wearable technology

allows clinicians to gather data about the home and community settings. Direct observations

concerning the impact of clinical interventions on mobility, level of independence, and quality of

life can be performed by means of wearable systems.

Some of the Examples of wearable Technology are given in the Sections 13.5.1- 13.5.3 that follows.

13.5.1 MIThril

MIThril is indicative of the functionality that can be expected in next generation wearable devices.

Apart from the hardware requirements, which include having a wide range of sensors with

sufficient computing and communication resources, and the support for different kinds of

interfaces for user interaction, including a vest, the device is being designed in a manner that it

blends with the user’s ordinary clothing and is for a wide range of user behaviours and situations.

A simple example is a reminder delivery system, called Memory Glasses, which acts on user

specified reminders such as “During my next lecture, remind me to give additional examples of the

applications of computers”, and requires a minimum of the wearer's attention. Memory Glasses

uses a proactive reminder system model that takes into account: time, location and the user’s

current activities based on daily events that can be detected such as entering or leaving an office.

Figure 13-8 MIThril Jacket from MIT Media Lab.

13.5.2 Charm Badge

Whenever there are conferences, the people attending the conferences make a lot of contacts and

the exchange of contact information between people takes up a lot of time. The application of

wearable technology in this scenario helps in saving time. The product CharmBadge from Charmed

Technology is an electronic business card that can upload and transmit user information through

infrared technology. When people register for the conferences, they are given identity badges

which have the person’s information and areas of interest embedded in them. As the person

moves through the conference whenever there is a match of areas of interest, the badges flash

indicating that there is a match in the areas of interest and thereby gives the person scope of

conversing with the opponent. If the person chooses to converse, then during the scope of

conversation, the badges contact each other and keep track of the conversation time. This is

further expanded to exhibitions, where the person can keep track of the interesting products and

technologies at the stall. Then the information gets stored on to the computer at the conference

desktop for further processing (This application makes use of a protocol called Internet Protocol

Version 6 (IPV6)). The information is then transferred to a secure website from where the person

can download the required information and import them into his / her email application.

Figure 13-9 Charmed Badge Technology

13.5.3 Musical Jacket

Levi's musical jacket is made with the silk organza and is controlled with an all-fabric capacitive

keyboard. This keyboard has been mass-produced using ordinary embroidery techniques and

conductive thread. The keypad is flexible, durable and responsive to touch. A printed circuit is

used to give the keypad a sensing ability, so that the controls react when pressed. The keypad can

sense touch due to the increase in capacitance of the electrode when touched. The keypads are

connected to a miniature MIDI synthesizer that plays music. Power could be supplied by a parasitic

power source such as solar power, wind, temperature or mechanical energy from turning wrists or

walking. Currently researchers are looking for fabrics capable of generating power as they flex.

Figure 13-10 Musical Jacket Keypad from MIT Media Lab

13.6 Grid Computing

In simplest terms, grid computing is the pooling of all IT resources into a single set of shared

services for all enterprise computing needs. Grid computing infrastructure continually analyzes

demand for resources and adjusts supply accordingly. It works on the principle of applying the

resources of many computers in a network to a single problem at the same time – usually a

scientific or technical problem that requires a great number of computer processing cycles or

access to large amounts of data for solving problems too intensive for any stand-alone machine.

Figure 13-11Grid Computing

Grid computing uses software to divide and process pieces of a program to as many as several

thousand computers. A number of corporations, professional groups and university consortia have

developed frameworks and software for managing grid computing projects.

Perhaps the most ambitious is Oxford University's Centre for Computational Drug Discovery's

project that utilizes more than one million PCs to look for a cancer cure. People around the world

donate a few CPU cycles from their PCs through "screensaver time." The project eventually will

analyze 3.5 billion molecules for cancer-fighting potential. More than 50,000 years of CPU power

(based on a 1.5 gigahertz chip) have been put to work so far. Other examples include SETI.

Bio-informatics* is another area where grid computing is very useful. Grid computing is used in

genome projects** .

*Bio-Informatics is the use of computers in solving information problems in the life sciences. It

mainly involves the creation of extensive electronic databases on genomes, protein sequences etc.

Also involves techniques such as three-dimensional modeling of bimolecular and biological systems

**Genome is the total genetic composition of an individual. The complete genetic information possessed by an organism.

13.7 New Trends

13.7.1 Smartcards Technology

A smart card, a type of chip card is a plastic card embedded with a computer chip that stores and

transacts data between users. This data is associated with either value or information or both and

is stored and processed within the card's chip, either a memory or microprocessor. The card data

is transacted via a reader that is part of a computing system. Smart card-enhanced systems are in

use today throughout several key applications, including healthcare, banking, entertainment and

transportation. To various degrees, all applications can benefit from the added features and

security that smart cards provide. Smart cards greatly improve the convenience and security of

transactions. They provide tamper-proof storage of user and account identity. Smart cards also

provide vital components of system security for the exchange of data throughout virtually any type

of network. They protect against a full range of security threats, from careless storage of user

passwords to sophisticated system hacks. Multifunction cards can also serve as network system

access and store value and other data.

Figure 13-12 Smart Card

The most common smart card applications are:

Credit cards

Electronic cash

Computer security systems

Wireless communication

Loyalty systems (like frequent flyer points)

Banking

Satellite TV

Government identification

13.7.2 Biometrics

Biometrics refers to the automatic identification of a person based on his/her physiological or

behavioral characteristics. This method of identification is preferred over traditional methods

involving passwords and PIN numbers for various reasons: The person to be identified is

required to be physically present at the point-of-identification; Identification based on

biometric techniques obviates the need to remember a password or carry a token. With the

increased use of computers as vehicles of information technology, it is necessary to restrict

access to sensitive/personal data. By replacing PINs, biometric techniques can potentially

prevent unauthorized access to or fraudulent use of ATMs, cellular phones, smart cards,

desktop PCs, workstations, and computer networks. PINs and passwords may be forgotten,

and token based methods of identification like passports and driver's licenses may be forged,

stolen, or lost. Thus biometric based systems of identification are receiving considerable

interest. Various types of biometric systems are being used for real-time identification, the

most popular are based on face, iris and fingerprint matching. However, there are other

biometric systems that utilize retinal scan, speech, signatures and hand geometry.

A biometric system is essentially a pattern recognition system which makes a personal

identification by determining the authenticity of a specific physiological or behavioral

characteristic possessed by the user. An important issue in designing a practical system is to

determine how an individual is identified. Depending on the context, a biometric system can be

either a verification (authentication) system or an identification system.

Figure 13-13 A computer mouse with a built-in fingerprint scanner (Source

Siemens)

Biometrics is a rapidly evolving technology which has been widely used in forensics such as

criminal identification and prison security. Recent advancements in biometric sensors and

matching algorithms have led to the deployment of biometric authentication in a large number

of civilian applications.

(a) (b) (c)

Figure 13-14 (a), (b) and (c) illustrate the use of biometric in Face Recognition, Iris Recognition and

hand geometry matching respectively.

Biometrics can be used to prevent unauthorized access to ATMs, cellular phones, smart cards,

desktop PCs, workstations, and computer networks. It can be used during transactions

conducted via telephone and Internet (electronic commerce and electronic banking). In

automobiles, biometrics can replace keys with key-less entry and key-less ignition. Due to

increased security threats, many countries have started using biometrics for border control

and national ID cards. However a biometric system which relies only on a single biometric

identifier in making a personal identification is often not able to meet the desired performance

requirements. Identification based on multiple biometrics represents an emerging trend. A

multimodal biometric system, which integrates face recognition, fingerprint verification, and

speaker verification in making a personal identification, is a better option. This system takes

advantage of the capabilities of each individual biometric. It can be used to overcome some of

the limitations of a single biometrics. Preliminary experimental results demonstrate that the

identity established by such an integrated system is more reliable than the identity established

by a face recognition system, a fingerprint verification system, and a speaker verification

system.

13.7.3 Telemedicine

As the health care system continues to change and adapt to the new realities associated with

finance and management restructuring, the technological side of patient care also has changed.

Telemedicine is the use of electronic information and communication technologies to provide and

support health care when distance separates the participants. It is a system that connects primary

care physicians, providers, specialists and patients. Telemedicine is not a new concept. It has

existed for a number of years in the form of the telephone and fax machines. In recent years, with

the improvements made in access, technology, and communications systems, telemedicine has

expanded and, in a time of limited resources, has become a feasible alternative for smaller and

rural medical facilities to provide routine and specialized services. Particularly in rural areas, it

offers the potential of both improved access to care and improved quality of care. The primary

applications of telemedicine are clinical, educational, administrative, and research. Clinical

applications include initial patient evaluations, diagnosis (telediagnosis), and consultation

(teleconsultation). Physician supervision of non- physicians and monitoring of patient status are

possible. Continuing education for professionals is available, as is patient and community

education (tele-education). Administrative uses, such as conferences, scheduling, and utilization

and quality review may be provided. Research is enhanced by aggregation of data from multiple

sources and coordination. Telemedicine allows access to the wealth of information available on the

Internet. This allows information to be at the touch of a finger. The availability of e-mail allows an

efficient mechanism of communication between consulting and primary physicians. Communication

between facilities is enhanced.

Figure 13-15 A typical Telemedicine Scenario

Telemedicine allows patients to receive medical care in their own community. This increases the

financial viability of rural medical facilities and strengthens the rural economy by keeping the flow

of resources in local communities. Telemedicine assists in providing specialty care services to rural

areas and provides more efficient use of medical resources which may lessen the amount of travel

time for both patients and the specialist. Continuity of patient care is enhanced when the patient,

primary care physician, specialist and family members are involved during a consultation. Should

the patient be required to be transferred to an urban facility, they have already met the physician

who will be caring for them. Physicians and on-site care providers benefit as they receive quick

and efficient consultations. The sense of isolation experienced by rural physicians is also reduced.

The formation of health care networks between rural and urban facilities provides benefits to both.

Urban based facilities provide accessibility of health care to rural areas. However, there are

telemedicine networks where the excess capacity of rural facilities can be tapped into to benefit

urban patients. It is possible that during peak times rural physicians may be accessed via

telemedicine to provide more timely care to patients waiting in congested urban emergency

rooms.

13.7.4 Virtual Reality

An artificial environment created with computer hardware and software. To "enter" a virtual

reality, a user wears special gloves, earphones, goggles and/or full-body wiring. In addition to

feeding sensory input to the user, the devices also monitor the user's actions. The goggles, for

example, track how the eyes move and respond accordingly by sending new video input.

Virtual reality is well known for its use with flight simulators and games. However, these are only

two of the many ways virtual reality is being used today.

Medicine: A prototype surgical assistant for simulation of paranasal surgery has been

developed. During a simulated operation the system provides vocal and visual feedback to

the user, and warns the surgeon when a dangerous action is about to take place. In

addition to training, the expert assistant can be used during the actual operation to

provide feedback and guidance. This is very useful when the surgeon's awareness of the

situation is limited due to complex anatomy.

Architecture: There is virtual reality program has applications in the area of architecture and light engineering. With light simulation architects can examine how outdoor light will fall inside and outside their building before it is built. If the lighting needs to be redesigned, the architect can redesign the building on the computer and examine the new

outdoor light effects. In addition to outdoor light, lighting engineers use virtual reality to examine the effects of point lights, spotlights and other indoor light sources. An interior designer could examine how light will affect different room arrangements.

Weather Simulation: There is a system for weather forecasting which accepts data from meteorological services such as satellite data, statistically corrected forecast data, precipitation data and fronts information. It then analyzes this data and uses fractal

functions to create projections of storm systems. Using this system to visualize artificial clouds, meteorologists can predict weather with increased accuracy.

Chemistry: Real Mol is a program that uses virtual reality to show molecular models in an interactive, immersive environment. The scientist who uses the program wears a cyberglove and a head mounted display to interact with the molecular system. Using RealMol scientists can move molecules or protein chains to create new molecules. This is

useful in fields such as drug design. RealMol displays molecules in three ways: ball and stick model, stick model and CPK model. The molecules are rendered through a molecular dynamics simulation program.

Other Applications of Virtual Reality include Flight Simulator; Museums and Cultural Heritage; Financial Data and Training and Hubble Telescope

13.7.5 IP Television

With the advent of high speed networks resulting in high bandwidth, it is now possible to watch

television channels using the internet on either a computer or a television. The IP refers to a

method of sending information over a secure, tightly managed network that result in a superior

entertainment experience. IPTV allows the service provider to deliver only those channels that the

consumer wants at any given time -- unlike traditional television broadcasting, where every

channel is delivered to every home on the network. For the first time, it will be economical to

deliver a college football game to everyone who wants to see it, for example, rather than just a

particular local community. IPTV gives the viewer access not just to an event but to the

information related to it. Since the network is a secure data network, it allows the viewer the

ability to look up player-specific information right on the TV while watching a game. It also enables

the viewer to send photos or home movies from the computer right onto the television, message

his/her friends while the viewer watches a show "together" across great distances, and receive

caller ID information on the TV. It also allows the flexibility of watching the programs according

the convenience of the user or uses a cell phone to manage his/her children's TV viewing when

he/she is away from home. This service is being provided by Mauritius telecom in Mauritius to the

ADSL subscribers.

Figure 13-16 IP Television

The basic setup to use IPTV includes the venerable set-top box. The box will connect to the home

DSL line and is responsible for reassembling the packets into a coherent video stream and then

decoding the contents. This enables the users to view the channels on the television rather than on

the computer.

13.7.6 Digital Libraries

Digital library is a collection of digital objects. A collection of research papers is a typical example.

When this collection gets sufficiently large, users of the digital library cannot examine each paper

individually to find if its subject interests them. To address this problem, digital librarians create an

interface to stand between the content of the collection and the user. In a traditional library, an

example of this would be a card catalog - a collection of small cards that represent the larger

objects contained in the collection. These cards are more manageable than the books that they

represent.

In a digital library, there are a number of ways that we can present the digital collection to the

user. The first thing that we need to do is to describe each object in a manageable way. This

description is called metadata - data (the description) about data (the digital object). This

metadata is more manageable than the digital objects that it represents. Metadata is written in a

standard format. This allows the metadata to be manipulated using automated tools.

A digital library is like a “regular” library except: contents digitized, services computerized, and clientele delocalized. A digital library also has mechanisms and policies for forming/managing combinations of contents, services, and clientele computationally automated/enhanced. The purpose of a digital library is to provide access to digital content in a variety of formats.

Figure 13-17 Google’s Digital Library

13.8 Further readings

O’Leary T, O’Leary L., “Computing Essentials”, complete edition, McGraw-Hill, 2004.

Capron H.L., Johnson J.A., “Computers, Tools for an information age” eighth edition,

Prentice Hall, 2004.

ACM website, www.acm.org, 2006.

BCS website, www.bcs.org, 2006.

IEEE website, www.ieee.org, 2006.

National computer board website, http://ncb.intnet.mu, 2006.

Computer Ethics Institute website, http://www.brook.edu/its/cei/overview/main.htm,

2006.

MIThril www.media.mit.edu/wearables/mithril/, 2006

Charmed Technology http://www.charmed.com/products/charmbadge.html, 2006

Grid Computing www.gridcomputing.com, 2006

Biometrics http://biometrics.cse.msu.edu/info.html, 2006

Biometrics http://biometrics.cse.msu.edu/multi_bio.html, 2006

Telemedicine www.med.und.nodak.edu/depts/rural/pdf/whatistele.pdf, 2006

Virtual Reality http://coe.sdsu.edu/eet/articles/VRApps/start.htm, 2006

IPTV http://www.iptvdictionary.com/, 2006

Exercises

Multiple Choice Questions

1. Carpal tunnel syndrome is an example of

(a) Health hazard resulting from wrist malformation

(b) RSI involving repetitive strain imposed on wrist

(c) Eye strain

(d) Back pain

(e) Torso pain

2. Which devices are most likely to cause health problems to a computer user?

(a) Chair, monitor, table and mouse.

(b) Chair, monitor, table and keyboard.

(c) Chair, mouse, table and keyboard

(d) Table, mouse, monitor and keyboard

(e) Table, scanner and printer

3. Which of the following is not a good practice when working on a computer?

(a) Taking frequent short breaks

(b) Set the keyboard at a height that allows your arm to remain comfortable.

(c) Work in brightly lit room

(d) Having the monitor much above eye sight level.

(e) Using an ergonomic keyboard

4.________ is concerned with finding ways to adapt a task to an individual rather than forcing the

person to adapt to the task.

(a) Social engineering

(b) Ergonomics

(c) Health monitors

(d) Human resource department.

(e) Workflow management

5. Data Protection Bill 2004 of Mauritius sets out

(a) Regulations for safe transactions among consumers and suppliers over networks

(b) Rules that govern the capture, transmitting, manipulating, recording and storage of data

relating to individuals

(c) Specific legislation for penalties involving cyber crimes

(d) provide the appropriate legal framework for the protection of intellectual property rights

(e) None of the above

6. __________ deals with electronic signature recognition.

(a) Computer misuse and cyber crime Act 2003

(b) Electronic Transaction Act 2000

(c) Copyright Act 1997

(d) E commerce Act 2001

(e) Data Protection Bill 2004

7. Which of the following will prevent someone from using materials you published over the

Internet without your permission?

(a) Patent

(b) Trademarks

(c) Copyright

(d) Plagiarism

(e) None of the above

8. Ethics in general

(a) Is a segment of the law to protect computer users

(b) Cannot be applied without law

(c) Complements the law by specifying good moral conduct

(d) Concerns only computer specialists

(e) Does not concern any of the above

9. _________ is a professional organization that sets out ethical guidelines for its members

(a) ACN

(b) BCC

(c) IIEE

(d) BCS

(e) ACC

10. Which of the following is an ethical behavior?

(a) Copying the power point assignment of your friend without his consent

(b) Copying the power point assignment of your friend with his consent

(c) Not using a computer that is running a simulation for a final year project in the university

computer lab.

(d) Randomly deleting files on a university computer lab.

(e) Downloading and saving illicit materials on university computer labs.

Exercises

Open Ended Questions

1. Computer use is associated with various health hazards. List and describe some of them.

2. Explain what ergonomics is and provide for recommendations related to a healthy and

productive environment for using computers.

3. What is the importance of taking short breaks when working for long periods on computers?

4. List and describe some common misuses of IT.

5. Explain the need for a legal framework in relation to IT use. List and describe some common IT

laws that exist in Mauritius.

6. What is copyright?

7. Describe what ethics relate to. Provide short examples of ethical behavior regarding computer

use.

8. If IT laws do exist, why is there a need for ethical guidelines?

9. Explain the term wearable technology. List and describe a few examples of wearable

technology.

10. IP television is a new trend in IT. Explain the term IPTV.

Chapter 2

Stepping in the Computer

Learning Objectives Upon completion of this unit, you should be able to do the following: 1. Identify the different components of a computer. 2. Understand how these different components work individually and how they integrate with each other.

3. Choose the appropriate components for a PC.

4. Understand how to build a computer.

Overview What is a computer? It is a device that processes data and converts it to meaningful information. So, it needs to acquire the data, process it and then output information – which means it needs input devices, output devices and a processing unit (and backing storage devices to store additional information).

To process that data, there needs to be a sort of brain that can analyse information; this brain is found inside the system unit which contains many pieces of electronics among which the most important are arguably the processor, motherboard, memory and graphics card.

Stepping in the Computer

2.0 Introduction Everyone has seen a computer but how many people have opened one and know how it works? Very few. In this chapter, we will attempt to understand how a computer works and we will also see the basics of assembling a computer.

2.1 Main Components of a Computer A computer is a device that accepts inputs and transforms them into outputs. The “input” is raw, unprocessed data that we feed into the computer and the “output” is the processed information that results.

A computer system can be represented as follows:

Figure 2-1 Simple block diagram of a Computer System

As can be seen in Figure 2-1, a computer is made up of four components:

Input

Process

Output

Backing Storage

2.1.1 Input and Output Input devices are used to enter data into a computer. The most common examples are the mouse and the keyboard. Output devices are used to display the data processed by the computer. The most common output devices are the monitor and the printer.

2.1.2 Backing Storage Backing storage devices are used to store data processed by the computer. For example, a bank stores data and information about its customers (name, bank account number, address,...) on a backing storage device. Common backing storage devices include hard disks, CDs and DVDs.

2.2 System Unit The System Unit is the core part of the computer. It contains the components that will process the data entered through input devices and will output meaningful information. The System Unit is contained inside a casing as shown in Figure 2-2.

Figure 2-2 Computer – inside view

Does all this mess appear scary? To the uninitiated yes, but the apparently chaotic world is

precisely ordered as we will see in the next sub-sections.

2.2.1 Processor The processor is the brain of the computer; it processes data and converts it into meaningful information. Arguably it is the most important component of the computer. It is jam packed with

electronic components called transistors and it operates at very high speeds. The speed of the processor will normally determine how fast data is processed by the computer – a 3 Ghz processor means that 3 billions operations are being performed per second (this is sometimes referred to as the clock speed of the computer).

Computer Speeds

The number of calculations that a computer can perform is normally a good indicator of the

power of a computer:

1 Mhz (Megahertz) means that the processor can do 1 million operations per second

1 Ghz (Gigahertz) means that the processor can do 1 billion operations per second

However, it is important to note that speed is not everything when evaluating the performance

of a computer!

There are two major manufacturers of processors for Personal Computers: AMD (AdvancedMicro Devices) and Intel (Integrated Eletronics).

Figure 2-3 Intel Pentium 4 (left) and AMD Processor (right)

A processor is a very compact device. It contains millions of transistors arranged compactly, very

very close to each other. For example, a Pentium 4 processor contains 55 millions transistors1 .

These transistors will work together to allow the CPU (Central Processing Unit – another name for

processor) to process information.

The CPU is made up of two main parts:

ALU (Arithmetic and Logic Unit) – which performs mathematical calculations

Control Unit – which controls the operations of the computer

Figure 2-4 Detailed Block diagram of the Computer System

In addition to those, the processor contains registers, which are small memory units located inside

the processor itself. These store intermediate results of calculations.

To process data, the Fetch-Execute-Cycle is used – sometimes called Fetch-Decode-Execute Cycle.

The processor is always looping through this cycle. For example, to add two numbers, the Fetch-

Execute-Cycle is executed as follows:

Fetch:

o the add instruction ( + ) and the operands (the numbers to be added) are fetched from

memory and stored in the registers (all data and instructions in a computer are stored in

memory)

Decode:

o the add instruction is then decoded - this is done by the Control Unit which sends

appropriate signals

Execute:

o the ALU will then perform the addition operation

2.2.1.1 Data representation Data inside the computer is represented as a series of 0's and 1’s, which are called bits. A bit is either a 0 or a 1. Bits can be grouped into bytes; a byte consists of 8 bits and bytes can then be grouped into Kilobytes (KB) – 1 KB = 1024 bytes.

Note: KB means 1024 bytes while kB means 1000 bytes This grouping hierarchy is best shown in the Table 2-1 below:

1 Byte 8 Bits

1 Kilobyte (KB) 1024 Bytes

1 Megabyte (MB) 1024 KB

1 Gigabyte (GB) 1024 MB

1 Terabyte (TB) 1024 GB

Table 2-1 Data Classification

Inside the computer, both data and instructions are represented as 0s and 1s as this is the

only thing that a computer understands.

Decimal and Binary

Human beings have ten fingers and when we count, we use our fingers to count in sets of ten.

We use what is known as the decimal system (0, 1, 2, 3, 4, 5, 6, 7, 8, 9).

The computer does not have any fingers; it uses digital electrical signals which can only be On

(1) or Off (0). So the latter can only count in sets of two and so uses the binary system (0, 1).

Another number representation system is the hexadecimal system. Here we count in sets of 16

(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F)

2.2.1.2 Trends in CPUs According to Moore's Law, the number of transistors in a processor is supposed to double every 18

months. For quite some years, this law has been duly respected but since transistors are physical components made of atoms and molecules, there is a limit to which they can be miniaturized. Eventually in the last few years, we have not been able to double the number of transistors as we would have liked to and so we have had to find new ways to increase the power of processors. These new ways have come under the name Hyper-threading, Dual Core and 64-bit processors which represent new ways of increasing the performance of processors.

Hyperthreading

A processor can execute only one instruction at a time during the Fetch-execute-Cycle. However,

with Hyper-threading, it is as if we have two processors (though we have only one) and so two

instructions can appear to be executed “at the same time”.

Dual Core

A Dual-Core processor physically has two processors into one packing for a processor. So, this

time, two operations can be really executed at the same time.

64-Bit processors

Previously micro-processors were referred to as 32 bits - the 32 bits refers to the size of the

registers (small memory units) in the processor. Recently Intel and AMD have introduced 64-bit

processors – the registers are now 64 bits long instead of 32 bits long. Thus more data can be

accessed directly from memory and also accessing the data is faster.

64-bit processors and programs

Though 64-bit processors can cope with 64-bit long instructions, we need programs than create

these 64-bit instructions. Right now (at the time this book is being written), only a few

Operating Systems can create 64-bit instructions and so 64-bit processors find themselves

underused.

2.2.1.3 Cooling the processor Processors have not only become more powerful in recent years but they also generate more heat. If we do not find a way of cooling them down, they will eventually burn!

Figure 2-5 Fan (black) on top of heat sink (grey)

So CPUs are normally equipped with a heat sink and a fan on top of the heat sink. The heat sink

will be placed on top of the CPU and normally some thermal paste is spread over the processor to

increase heat conductivity between the latter and the heat sink.

Figure 2-6 Processor with thermal paste applied on top

Overclocking the CPU

Overclocking means running your processor at a faster speed than designated by the

manufacturer. E.g. a 1.5 Ghz CPU is made to run at 1.7 Ghz. CPU are overclocked to get a

performance gain but as they work harder (they get more tired), they heat up more and so

need better heat dissipation mechanisms.

2.2.2 Memory Whenever software is installed on a computer, the latter is placed on the hard disk of the computer. However, when that software is run (e.g. when you double-click on its icon), the latter has to be transferred to the memory of the computer for the CPU to be able to execute it.

Memory in a computer is in the form of RAM (Random Access Memory) modules. RAM can be purchased in the form of RAM sticks and it is normally measured in terms of its size (256 MB,

512MB, 1 GB,...). RAM is said to be volatile, meaning that, information stays here as long as the computer is on but as soon as it is turned off, the information inside the RAM disappears.

2.2.2.1 Types of RAM The current type of RAM memory used in computer systems is referred to as DDR (Double DataRate) RAM. It has replaced the old SD (Synchronous Dynamic) RAM which was used some time back and it offers improved performance. DDR2 is the new type of RAM technology that is very likely going to take over from DDR RAM. However, it seems that we will have to wait a few more years to see this taking place completely. Intel has already adopted the DDR2 standard while AMD is still using DDR for now.

RAM Performance

The performance of a RAM module does not depend only on its size. There are other factors like

the speed at which the data can be transferred from the RAM to the processor (the frequency).

There's also the speed at which the data can be accessed inside the RAM.

Figure 2-7 SD, DDR and DDR2 RAM

2.2.2.2 Cache Memory The purpose of cache memory is to speed up a computer while keeping its price low. Cache exists in different forms in computer but it primarily refers to the small memory locations found on the

processor. There are usually two levels of cache in the processor of a computer; these are Level 1 cache (L1)

and Level 2 cache (L2). When a program is being run, it will take data from the hard disk and place it in the RAM. RAM is closer to the CPU and is also faster to access but yet, it is still slower than the processor. To speed things up even more, the data that are going to be worked with are transferred from the RAM to the cache which means that when a program is being executed by the CPU, the latter will look for information in the cache and not in the RAM. The problem is that the cache is very small (we do not have a lot of space on the processor to

have a big amount of cache) and so cannot store a lot of information. Therefore before trying to access data from the cache, we must first check if it is there – a cache hit. Else, we have a cache miss and we need to go retrieve the data from the RAM.

Cache Size and processor performance

The size of the cache is an important aspect that will determine the overall performance of

processor. The cache size usually quoted is that of the Level 2. For example, the size of the

cache on a Pentium 4 Northwood (the codename for that processor) is 512 KB.

Cache memory is arranged in a hierarchy as shown below:

Figure 2-8 Cache Hierarchy

The table below shows the approximate size of each component.

Memory Type Size

L1 Cache ~ 16 KB

L2 Cache ~ 512 KB – 2 MB

RAM 256 MB – 2GB

Hard Disk 60 GB – 200 GB

Table 2-2 Memory Type and Speed

Another domain where the term cache is often used is the web. Connecting to the Internet

(especially on a 56 KB modem) is very slow and also the data that we are trying to access might

be for example in Hawaii – making data retreival an even slower process. So to try to improve the

speed of accessing the page, that page can be stored in a web server in Mauritius the first time it

is accessed and the next time another user wants access to the same page, the latter’s browser

will not have to fetch the page from Hawaii but can instead get it directly from the web server in

Mauritius, thus speeding up data access.

2.2.3 The Motherboard The motherboard is at the heart of the computer; it links all the different components (processor, memory, graphics card,...) together. As can be seen from Figure 2.9, the motherboard is very complex and contains many small parts welded on it. We will now have a look at some of these different components.

Figure 2-9 The Motherboard2

2.2.3.1 The socket connection This is where the processor is connected to the motherboard. Different motherboards accept

different types of processors depending on the type of socket they have. For example, Pentium 4

processors are connected to a motherboard through “socket 478” while Athlon XP processors are

connected through “socket A” (also known as socket 462).

Figure 2-10 Socket 478 (left) and socket 462 (right)

2.2.3.2 The North Bridge and South Bridge The North Bridge and South Bridge are two controllers found on the motherboard.

The North Bridge controls the exchange of data between the processor, memory and graphics card. It is a high speed component that is usually equipped with a heat sink and a fan. The South Bridge controls exchanges of data between the PCI slots (in which will be plugged in the sound card, modem,...) and the backing storage devices.

North Bridge and South Bridge Cooling

The North Bridge and South Bridge are basically two small processors. So when they work they

tend to heat up and need cooling else they will burn.

2.2.3.3 Memory Banks This is where the memory modules will be connected on the motherboard. Memory banks can be single (DDR) or double sided (DDR2) allowing either single memory modules to be connected or requiring two memory modules next to each other respectively. The current trend in new motherboards is to have dual channels.

Figure 2-11 DDR slot

2.2.3.4 The AGP Slot The AGP (Accelerated Graphics Port) slot is where the graphics card will be connected to the computer. It is physically very close to the CPU and so allows rapid interchange of information. Current AGP slots found on motherboards are referred to as 8x – reaching a data transfer speed of 2Gbps.

2.2.3.5 PCI Slots PCI (Peripheral Component Interconnect) slots allow sound cards, network cards and modems to be connected to the computer. They are inherently slower compared to the AGP slot (transfers are of the order of 133Mbps).

2.2.3.6 PCI Express This is going to be the successor to AGP. It is available in different flavours ranging from 1x, 2x, 4x, 8x and 16x. They are going to be faster that PCI (1x operates at 250 Mbps) and they have

already started to replace AGP slots on motherboard – the 16x version has been reserved for graphics card and it is operating at 8Gbps (4Gbps in each direction)

2.2.3.7 IDE Connectors These connectors will allow Hard Disks, CD-ROM and DVD-ROM Drives to be connected to the

computer. Typically two devices can be connected to one IDE through the use of IDE (ATA) cables.

Figure 2-12 IDE Cable

2.2.3.8 Serial ATA (SATA) This is the new technology that is slowly replacing parallel ATA (IDE) connectors especially for hard disks. SATA I runs at 1.5Gbps resulting in a maximum transfer rate of 150 MBps while SATA II runs at 3.0 Gbps resulting in a maximum transfer rate of 300 MBps.

Figure 2-13 SATA Cable

2.2.3.9 Bus What is a bus?

Bus lines are what connect the different components found on the motherboard together. Data is going to flow along these lines. So the size of the bus and speed at which data can flow is a good

indicator of the performance of the motherboard – the processor needs data to work and it needs to get that data very quickly. Having a very fast processor and a very narrow and slow bus is useless - the processor will be idle while waiting for data to arrive. Front Side Bus The Front Side Bus (FSB) is what actually connects the CPU to the memory, graphics card and other components of the motherboard together. Modern motherboards typically have busses of

size 64 bits and a bus frequency of above 100 MHz. For example, Pentium 4 has bus of frequency 100/133/200/266 MHz.

The speed of the CPU is determined by applying a multiplier to the FSB.

“For example, a processor running at 550 MHz might be using a 100 MHz FSB. This means there is

an internal clock multiplier setting of 5.5; the CPU is set to run at 5.5 times frequency of the front

side bus: 100 MHz x 5.5 = 550 MHz.” 3

So, by altering the speed of the FSB, we can achieve different CPU speeds. This is the basis behind

overclocking a processor. The speed of the FSB and the multiplier can be set by modifying the

BIOS.

2.2.4 Graphics Card Graphics card are very important in modern computers – their job is to handle most of the graphics work that has to be done by the computer. As such, they will have a processor, (which is hidden under the heatsink and fan in Figure 2-14) also known as the GraphicalProcessor Unit (GPU) as well as some memory on the card to allow them to process graphical information.

Graphics cards are manufactured by two main companies nowadays: nVidia and ATI. Graphics card

used to come with AGP connectors but the current trend is to have PCI Express graphics card.

Figure 2-14 ATI Radeon 9800 Pro

2.2.5 Flash ROM The BIOS is stored in a component called the Flash ROM (Read Only Memory). Information stored in ROM is stored there permanently, meaning that even when the computer is turned off, the information stays there, in comparison to RAM which is volatile. There are several types of ROM memory:

PROM: Programmable Read Only Memory

o This type of ROM is programmed by a special device and information written onto it is permanently stored there

EPROM: Erasable Programmable Read Only Memory

o This is a type of ROM that can be erased through exposure to ultra-violet light

EAPROM: Electrically Alterable Programmable Read Only Memory o This type of ROM can be erased electronically but changes can only be made one bit at a time – so it is considered to be slow and thus rarely used

EEPROM: Electronically Erasable Programmable Read Only Memory

o An electronically erasable type of ROM that is sometimes referred to as Flash ROM. It

can be erased and rewritten to while it is inside the computer.

Flashing the BIOS

The BIOS contains instructions used to start the computer (a small program). Like any other

programs, there are sometimes improvements and corrections to be made to it. Flashing the

BIOS is the operation of replacing the instructions stored on the ROM by a set of more efficient

ones.

2.2.6 CMOS The Complementary Metal Oxide Semiconductor is a type of memory that works with the BIOS; it stores configuration information for the computer. A small battery is required since the CMOS needs a small source of power so that it does not lose any information. The CMOS is what you can access on pressing the “Delete” key (or some other key on the keyboard) when the computer is started. It is usually a blue screen arranged into menus that will allow changes made to the configuration of the computer.

2.2.7 Ports These are sockets that allow devices like keyboard, joystick, mouse and printer to be connected to

the computer. Different types of ports exist, each operating at different speeds and meant for different devices.

Figure 2-15 Ports on a computer

The table below shows the different ports in a computer

Port Use

USB (Universal Serial Bus) Connect Printers, Digital cameras, Pen drives - 480 Mbit/s (USB

2)

Firewire Connect camcoders, some harddisks - 400 Mbit/s

Serial Port Connect some types of modem – currently being replaced by

USB - 19200 bit/s

Parallel Port Connect printers - currently being replaced by USB

PS/2 Port Keyboards and mouse – currently being replaced by USB

Video Port Connect VGA monitors to the computer

DVI Connect LCDs to the computer

Modem Connect computers to the Internet – usually dial-up connection.

Network port Connect computers to networks

Power Connect the computer to power supply

Table 2-3 Memory Type and Speed

USB ports are connectors which are often used to connect digital cameras, scanners, printers,... to the computer. The USB (Universal Serial Bus) 2.0 allows transfer speeds of up to 480 Mbps. A technology similar to the USB is the FireWire which supports speeds of up to 800 Mbps.

Figure 2-16 FireWire (left) and USB (right) cables

2.2.8 Expansion Cards This is a general term used to refer to printed circuit boards that can be inserted into PCI slots on the motherboard of the computer. These cards provide additional functionalities to the computer, for example, dial up Internet access (modem), radio or TV on the computer (TV card)

2.2.8.1 Modem A modem is a device that allows a computer to be connected to the Internet. The modem can be an expansion card inserted on the motherboard of the computer or it can exist as an external device (external modem).

56 Kb modems are typically used for dial-up access in Mauritius. If faster connection is required, ADSL modem or the recently introduced WiMax (wireless) modem can be used.

2.2.8.2 Sound Card This is an expansion card that is plugged in on the motherboard that will allow us to have sound output. Speakers and Microphones are usually connected to it.

However, sound cards are very often integrated on the motherboard meaning that a separate sound card is not required.

2.2.8.3 TV Card This is an interesting option to add to a computer. Basically it will allow you to listen to radio and watch TV on your computer. It will contain a few plugs where an antenna can be connected for the radio and the TV. A software associated with the card will allow for tuning of the different radio and video channels.

2.2.8.4 Network card This allows a computer to be connected to a network. Normal 10/100 Mb Ethernet network cards are available that will allow a PC to connect to a network (like what you see in some Cyber Cafes and the university labs).

Another type of network card that is gaining a lot of popularity is the Wireless network card. It allows a computer to be connected to a network without requiring any physical cable.

2.3 Further readings

The PC Guide, http://www.pcguide.com/topic.html, last accessed: 06/05/06

Tom’s Hardware, http://www.tomshardware.com/, last accessed: 06/05/06

Exercises

Multiple Choice Questions

1. How many bits are there in 1 Kilobyte?

(a) 8 bits

(b) 1000 bits

(c) 1024 bits

(d) 8192 bits

(e) 1048576 bits

2. Which of the following is not a type of RAM?

(a) DDR RAM

(b) SD RAM

(c) DDR2 RAM

(d) EDO RAM

(e) AMD RAM

3. A processor is connected to the motherboard through a

(a) Socket

(b) Port

(c) Bus

(d) PCI slot

(e) Memory slot

4. Which of the following is NOT TRUE?

(a) USB cables can be used to connect printers and cameras to a computer

(b) A network port allows computers to be connected to a network

(c) Parallel ports allow monitors to be connected to a computer

(d) PS/2 ports allow keyboard and mouse to be connected to the computer

(e) FireWire can be used to connect camcoders and hard disks to the computer

5. How would you represent the decimal value 26 in Hexadecimal?

(a) 26

(b) 1A

(c) 11010

(d) 10

(e) A1

6. Which of the following is NOT TRUE about cache?

(a) L2 cache is faster than L1 cache

(b) A cache miss indicates that the information we are looking for is not in the cache

(c) RAM can be thought of as a cache for the Hard Disk

(d) L2 cache is bigger than L1 cache

(e) The size of L2 cache is approximately between 512 KB and 2 MB

7. AGP 8x looks likely to be replaced by _______________ ports in the near future.

(a) PCI

(b) PCI Express

(c) AGP 16x

(d) ISA

(e) SATA connectors

8. Which type of ROM is commonly used in modern PCs?

(a) PROM

(b) EPROM

(c) EAPROM

(d) EEPROM

(e) None of the above

9. Which of the following gives a list of memory in ascending order of speed access?

(a) RAM, Hard Disk, L1 Cache, L2 Cache (b) L1 Cache, RAM, Hard Disk, L2 Cache (c) L1 Cache, L2 Cache, RAM, Hard Disk (d) L2 Cache, L1 Cache, RAM, Hard Disk (e) Hard Disk, RAM, L2 Cache, L1 Cache

10. Which of the following is NOT a type of Personal Computer?

(a) Desktop computers (b) Laptops/notebooks

(c) PDAs (d) Minicomputer (e) None of the above

Exercises

Open-Ended questions

1. Describe the importance of cache in a computer. 2. Compare and contrast the features of the latest Intel Processor and the AMD Processor.

3. Compare and contrast among the PCI, AGP and PCI Express slots.

4. How can the BIOS on a computer be upgraded? 5. Identify the different ports on a computer and give an example of a use for each of them. 6. What components would be most important in building a PC that would allow you to play the

latest games? Discuss (Note: games are very greedy in terms of graphics resources) 7. Why is heat bad for the computer? What can be done to cool down the computer and the processor? 8. Suppose you want to assemble a PC to allow you to play the latest 3D games. What minimal configuration would be required for such a computer?

9. What is the Front Side Bus? How can it be used to overclock a computer?

10. What expansion card would you require for each of the following? (a) Allow you to watch TV on the computer (b) Allow you to connect to the Internet (c) Allow you connect to a network

Chapter 3

Input and Output Devices

Learning Objectives Upon completion of this unit, you should be able to do the following: 1. Understand the importance of current input and output devices in a computer system. 2. Explain the functionality and mechanisms of several input and output devices.

3. Identify other areas of application for specific input and output devices. 4. Evaluate and choose appropriate input and output devices.

Overview Computer input and output devices have undergone remarkable development since their existence. This chapter covers the different types of computer input and output devices.

The primary function of input devices is ‘getting’ data and instruction into the computer. Popular input devices are keyboard, mouse, scanner, microphone and webcam. An Output device is any

hardware component that can convey information to a user. Common output devices are monitors, printers and sound speakers

Input and Output Devices

3.0 Introduction Input devices accept user commands or data and send them to the computer for processing.

Typical input devices are keyboard, mouse, scanner and microphone. On the other hand, output

devices accept results or information generated by the computer, and present this to the user in a

variety of means (both audio and visual e.g. textual, image, video). Typical output devices are

printers, monitors and speakers. Some special devices can be used for both input and output, such

as floppy disks and hard drives. Computer input and output devices have undergone remarkable

development with advances in technology.

3.1 Input devices With all the input devices available today, users may find it difficult to determine which one is best

for entering data into their personal computer. The main function of input devices is to convert people-readable form of data into a machine-readable form that the computer can store and process. People readable form of data can be letters, numbers, visual codes and symbols. Machine-readable forms of data consist of electronic signals of 0's and 1's. A personal computer is normally equipped with a mouse and keyboard as standard input devices. Input devices can fall

under three categories, namely pointing, scanning and voice. Input can be made by keyboard or direct entry.

3.1.1 Keyboard Most modern computer keyboards are based on the QWERTY layout, and resemble a typewriter keyboard except that they have extra keys for certain special functions, such as:

Function keys: located at the top of the keyboard with prefix F, example F1, F2 and so on.

However, these shortcuts on depends on the specific software used.

Numeric keypad: located on the right corner of the keyboard, is a separate set of number keys,

like that of a calculator, for quick input of numbers and arithmetic operators.

Arrow keys or navigation keys: located between the main keypad and the numeric keypad, are

used to move the cursor up, down, left, and right.

Insert, delete, page up, page down keys: located above the arrow keys, are used in word

processing for performing insert, delete, page up, and page down.

Figure 3-1 Keyboard

In recent years, so called “Internet keyboards” have also become popular. These include extra

buttons for specific applications or functions like e-mail client or browser.

Ergonomic keyboard have features designed to reduce the effects of occupational overuse

syndrome (formally known as Repetitive Strain Injury). An example is the split keyboard,

illustrated in Figure 3-2, which offers infinitely adjustable positioning.

Figure 3-2 Split Keyboard

The trend now is wireless keyboard design that offers more freedom for the user. Rather than

being tied to a computer, forced to sit perhaps in an uncomfortable position for hours sometimes,

wireless keyboard can be placed comfortable anywhere on the table or on the lap

3.1.2 Mouse A mouse is a pointing device, as shown in Figure 3-3. It is used to move an electronic pointer called a cursor around the screen or click on an object or option on the screen to trigger it to respond. The mouse is now present in virtually every office environment because of the predominance of graphical user interface (GUI).

Figure 3-3 A mouse

Types of mouse A mechanical mouse has a rubber or metal ball on its underside. When the ball rolls in a certain direction, electronic circuits in the mouse translate the movement into signals that are sent to the computer. An optical mouse has gained widespread adoption by eliminating the need for a special mouse pad. It has no moving parts; instead it uses light emitting diodes and photodiodes, that emit and

sense light to detect the mouse’s movement. An optical mouse can be used on nearly all surfaces, is more precise than a mechanical mouse, and does not require cleaning. A cordless mouse, or wireless mouse, is a battery-powered device that transmits data using wireless technology, such as radio waves or infrared light waves. A cordless mouse uses technology very similar to that of a wireless keyboard. Apart from the regular mouse that is operated by the hands, other mouse variants exist. These

cater for people who may feel uncomfortable with traditional designs

The trackball is sometimes called an upside-down mouse. While a mouse employs a rolling ball on

its underside, a trackball uses an exposed ball that the user manipulates with his or her fingers. Unlike a traditional mouse, a trackball does not require a horizontal pad on which to move. Trackballs are a good choice for those with limited desk space, large monitors or poor gripping ability.

Figure 3-4 Trackball

Foot mouse (also called no hands mouse) is a mouse variant for those whose hands are injured due to Carpal Tunnel Syndrome or mouse overuse fatigue. It can eliminate stress related to the

wrist, elbow and shoulder. These innovative “no hands” mouse uses two interchangeably foot pedals; one to move the cursor and the other one to click, drag and drop objects on the computer desktop. It is also a more productive mouse since users can keep typing without having to jump between the keyboard to the mouse and back.

Figure 3-5 Foot Mouse

3.1.3 Touchscreen A touchscreen is an intuitive computer input device that works by simply touching the display screen, either by a finger, or with a stylus, rather than typing on a keyboard or pointing with a mouse. A stylus is a "pen" that does not write! The stylus point is made of a firm but non-scratching plastic to "write" on screen. Touchscreen is a pointing input device that allows the user

to select actions and commands with the finger. It consists of a special type of visual display unit (VDU), which has a grid of light beams or fine wires criss-crossing the screen. When the screen is touched (usually to choose an on-screen option), the computer senses where on the screen it has been pressed to respond. The touch-sensing mechanisms can use optical, electrical or acoustical methods to determine the co-ordinates of the touch.

Any touchscreen system comprises the following three basic components:

a touchscreen sensor panel, that sits above the display and which generates appropriate

voltages according to where, precisely, it is touched.

a touchscreen controller, that processes the signals received from the sensor and

translates these into touch event data which is passed to the PC's processor, usually via a

serial or USB interface.

a software driver, provides an interface to the PC's operating system and which translates

the touch event data into mouse events, essentially enabling the sensor panel to "emulate"

a mouse.

The touchscreen interface is simple, intuitive, and easiest to learn of all PC input devices. It is fast

becoming the interface of choice for a wide variety of applications, such as Public Information

Systems, Information kiosks, tourism displays, and other electronic displays are used by many

people that have little or no computing experience. The user-friendly touchscreen interface can be

less intimidating and easier to use than other input devices, especially for novice users, making

information accessible to the widest possible audience.

One disadvantage of touchscreen is that using the finger to point is not always suitable for

accurate selection of small regions and it can leave greasy marks on the screen.

Figure 3-6 Touchscreen

.1.4 Touchpad A touch pad feels less mechanical than a mouse or trackball because the user simply moves a finger on the pad. A touch pad has two parts. One part acts as a button, while the other emulates a mouse pad on which the user traces the location of the cursor with a finger and striking over the

surface. People with carpal tunnel syndrome find touch pads and trackballs easier to use than mice. Many portable computers have built-in trackballs or touch pads as input devices. However, even experienced users continue to report problems, if another finger accidentally touches the pad causing motion detection to become confused and the cursor to jump across the screen.

Figure 3.7 Touchpad of Laptop

3.1.5 Light pen A lightpen is a pointing device that is held to point directly to items on the screen. This light

sensitive pen addresses individual pixels for fine selection and drawing. Hence, it is much more accurate than the touchscreen. Some limitations of the fragile lightpen are that it may be tiring on the arm, can cause obstruction of sight on the monitor and varying background lighting often corrupts lightpen input.

Figure 3-8 Lightpen

3.1.6 Digitizing tablet or digitiser A Digitising tablet is a device that facilitates the accurate input of 2-D or 3-D drawings and designs. A drawing can be placed directly on the tablet, and the user traces outlines or inputs coordinate positions with a hand-held cursor or stylus. For digitizing tablets, each point on the

tablet represents a point on the display screen in a fixed manner. This differs from mouse, in which all movement is relative to the current cursor position. The static nature of digitizing tablets makes them particularly effective for tracing complex drawings by designers, engineers and

architects. Digitizing tablets are also called digitizers, graphics tablets, touch tablets, or simply tablets. Modern graphics tablets are widely considered to offer a very natural way to create computer graphics. They have stylus-based interface with ability to detect pressure, tilt and other attributed of the stylus and its interaction with the tablet

Figure 3-9 Digitising Tablet

3.1.7 Scanner A scanner is a device which scans documents containing text or graphics and converts them into a bitmap (digital picture image). Most scanners today are variations of the desktop or flatbed scanner that allows documents to be placed on a flat scanning surface.

Figure 3-10 A Flatbed Scanner

A flatbed scanner works as follows:

A light source illuminates the paper, and light is reflected off the paper down onto the

scanning mechanism.

Blank or white spaces reflect more light than darker areas.

A motor moves the scanning head underneath the page along its length.

As the scan head moves down the page, it captures the reflected light bounced off the

page.

The light captured from the page is reflected through a series of mirrors.

A lens assembly focuses the light beam from the mirrors onto a light sensitive array that

converts the light into electrical signals.

The electrical signals are converted into corresponding dots. In a colour scanner, the light

is passed through red, green and blue filters in order to extract colour information.

The converted dots is sent to the computer for storage.

A hand held scanner is held with the hand and is moved slowly down the document or object,

scanning it as it moves. The scanner should be moved at a constant speed without starting or

stopping or jerky movements in order to obtain best results.

Figure 3-11 A Hand-held Scanner

Modern scanners can generate large volume of data in a matter of seconds. Therefore, fast

connection between scanner and PC is required, such as USB connections.

3.1.8 Barcode reader As illustrated in Figure 3-12, barcodes consists of different groups of vertical bars that can be read by an optical scanner. They are printed on nearly every product. Supermarkets use barcode

reader or scanner to read data from a product item barcode and transfer it to the processor to

determine price and product details. They are cheap to produce and very durable.

Figure 3-12 Barcode(Left) and Barcode Reader(Right)

3.1.9 Image and video input devices The digital camera records and stores photographic images in digital form that can be fed to a computer for viewing and printing.

A web camera (or webcam) is a real-time camera whose images can be accessed using the PC

video software application. The images can be uploaded to a web server, either continuously or at

regular intervals. Videoconferencing applications can use a webcam connected directly to a PC.

Today there are thousands of webcams that provide views of homes, offices and other buildings as

well as providing panoramic views of cities. Special webcams are used to monitor traffic, weather

and even volcanoes. The video feeds obtained from webcams are uploaded to a computer where it

can be processed using appropriate software.

3.1.10 Audio input device A microphone is a transducer that converts sound into an electrical signal for recording onto computers. It is very popular as a sound input device and is used with multimedia applications

such as for voice recording; speech recognition, Iinternet telephony and teleconferencing. Microphones now come as headsets, USB microphones or Bluetooth and wireless headset.

(a)

(b)

Figure 3-13 (a) Bluetooth wireless headset (b) USB microphone.

3.1.11 Wired gloves One of the mainstays of the new virtual reality systems is the wired glove, a 3-D input device. It consists of a special lycra glove with sensors to determine the 3-D positional information. The potential for the wired glove is vast; gesture recognition and sign language interpretation are two main applications. Various sensor technologies are used to capture physical data such as bending of fingers. Wired gloves are often called “data gloves” or “cyber gloves”, but these two

terms are trademarks.

Figure 3-14 A Data Glove

The fundamental task in computer input is to transfer information from the brain of the user to

the computer. Progress in this discipline attempts to develop better human-computer interface

by seeking faster, more natural and, convenient means for a user to transmit information to a

computer.

3.2 Output Devices Output devices have evolved over time. They are not as numerous as input devices but their efficiency is much appreciated in the computer technology world. The basic function of an output device is to get information or any other response out of the computer.

3.2.1 Display devices Monitor screens are devices used to display information from the computer. In fact, television sets include monitor screens, though in general, the monitor screens used in computer systems are of a much higher quality.

Monitors come in various sizes, commonly starting at 14 inch, then 15 inch, as well as 17 and 19

inch. This is the size of the viewable screen measured across the diagonal from corner to

corner. Resolution of the monitor screen refers to the number of dots, called pixels, displayed in

the horizontal and vertical display area. Typical screens are capable of displaying 640 x 480 or

1024 x 768 pixels. The greater the pixel density, i.e. the number of pixels per unit area on the

monitor screen, the better the resolution. Hence, higher resolution produces higher display quality.

Another term used with monitors is refresh rate. This refers to the number of times per second

that the image is redrawn on the monitor screen. A refresh rate of 60Hz means the images is

redrawn 60 times a second. Higher refresh rates are required for larger resolutions, else the

viewer tend to see the image on the screen flicker. The images on the screen have to be refreshed

at a reasonable rate (greater than 50Hz); otherwise the human eye perceives the image as

flickering.

Another measurement of resolution is the dot pitch, the distance in millimeters between pixels.

The smaller the dot pitch the better the resolution. The signal to a display screen comes from

a video card or graphics card. This card converts digital output to analogue signals for the

display. The Video Electronics Standards Association (VESA) develops standards for video

displays. Most monitors are at least SVGA (Super Video Graphics Array) with 1280 x 1024

resolution and laptops with XGA (Extended Graphics Array) for higher resolution.

The number of colours that a video card can display is determined by its bit depth or colour

depth. This is how many bits it uses to store the colour of one pixel. An 8-bit card will only allow

256 colours. Most cards today are at least 24-bit and can display 16.7 million colours.

3.2.2 Liquid Crystal Displays (LCD) and Cathode Ray Tube (CRT) Monitors There exist two types of monitors: Cathode Ray Tube (CRT) and Liquid Crystal Display (LCD). Modern laptop computers use LCDs similar to those used in calculators and watches. This type of display has also become popular in larger formats with desktop computers because of their compactness. They take up less space and are lighter than most CRT monitors. LCDs can be used in many places where a larger CRT monitor cannot fit. Other advantages of LCDs are the absence of electromagnetic waves, lower heat emission and power savings over the CRT. LCD monitors exist in monochrome or colour. The screen is perfectly flat, with no distortions due to a curved

screen like CRTs. Most new LCDs connect to standard video cards, although a few require their own graphics adapters. Disadvantages of the LCD monitor are the higher cost, image dimness, small viewing angle and slower response times. All of these disadvantages are being addressed as new technology is applied.

LCD display is based on a totally different technology than CRTs. An electric current is passed

through a liquid crystal solution between two sheets of polarizing material. As the current passes

through, it causes the crystals to align so that light cannot pass through them. The image appears

as some crystals allow light to pass through and others do not.

(a)

(b)

Figure 3-15 (a) LCD and (b) CRT Monitor

3.2.3 Printers By far, paper is the single largest output from computers. A printer is a device that produces a

hardcopy (permanent human-readable text and graphics, usually on paper or transparencies) from data stored in a computer connected to it. Modern printers come in a variety of types, with many capabilities.

Printer outputs are produced by impact or non-impact methods. Impact printers, such as dot-matrix, rely on the forcible impact of pins that presses against an inked ribbon onto paper to form a character or symbol, like a typewriter. Non-impact printers, like inkjet, laser and thermal printers, do not involve physical contact of mechanical device striking on the paper. Instead, they use ink spray or toner powder. Dot-matrix printer Dot Matrix printers rely on a matrix of pins or dots and they have survived the market changes in technology, due to their application as impact printers. This means that they are able to print on multipart paper using carbonless copy paper, which is used extensively in the accounting and auditing sector, and other businesses that need to keep accurate records and legal copies of

documents. However, even for sales invoices or receipts printing, dot-matrix printers are now rapidly being superseded by other types of printers. Figure 3-16 shows a dot matrix printer used in office.

Figure 3-16 Dot Matrix Printer.

The main features of dot matrix are tabulated in Table 3-1.

Mechanism

It has a mechanical print head that travels across the paper. The head has a

set of pins which are pushed out to form the shape of each character. The

pins hit an ink ribbon against the paper as the print head moves along.

Different coloured-ink ribbons can be used.

Uses

Limited to situations where carbon copies are needed and the quality is not

too important. Typical uses might be for very high volume applications like

invoice printing.

Advantages

The purchase cost is low and the running costs are very low. They can

print fairly quickly, when multiple copies are being printed in one print run.

They are robust and can operate in harsh environments. If several sheets

of self-carbonating paper are placed into the printer then the impact will

produce multiple copies.

Disadvantages

The printing quality is low - these printers produce low to medium quality

black and white printing, and can only print low resolution graphics. These

printers can be quite noisy.

Table 3-1 Dot Matrix Printer Features

Inkjet printers

Figure 3-17 Inkjet Printer

The main features of an Inkjet printer are tabulated in Table 3-2.

Mechanism

The print head contains tiny nozzles through which different coloured inks

can be sprayed onto the paper to form the characters or the graphic images.

The ink is forced out by heat or by tiny piezoelectric crystals which change

shape when an electric current is applied across them.

Uses A popular choice for home and school use where small amounts of printing

are done and colour printing is only occasionally needed.

Advantages

These printers are relatively inexpensive and produce high quality black

and white or colour printing. Relatively quiet printing and better output

compared to dot matrix.

Disadvantages

The ink cartridges can be expensive so running costs can be high.

Theprinting speed is slow compared to a laser printer. Ink can be smeared

on paper.

Table 3-2 Inkjet Printer Features

Laser printers

Figure 3-18 Laser Printer

The main features of a Laser printer are tabulated in Table 3-3.

Mechanism

These print in the same way as photocopiers. The powdered ink (toner), is

transferred to the paper and then fixed by heat and pressure.A school or

business printer would have a typical speed of 10 to 20 pages per minute

(ppm).

Uses Common wherever fast, high quality printing is required.

Advantages

They are quiet and fast and produce high quality printouts.

Running cost are low because although toner cartridges are expensive to

replace, they last a long time.

Disadvantages

Laser printers are more expensive than ink-jet printers (but the difference is

narrowing). Toner cartridges are expensive to replace.

(but their speed and high quality output means they are becoming more

popular).

Table 3-3 Laser Printer Features

When buying a printer, users should evaluate relative purchase costs, running costs, quality and

speed of different types of printers.

3.2.4 Plotters Plotters are devices, used by artists, designers or architects for producing multi-colour, high quality drawings such as architectural plans, charts and maps.

Pen plotters print their output by moving a pen across the surface on paper larger in size than

used for printers. They can draw precise and complex line art, including text, but very slowly because of the mechanical movement of pens. Thermal and laser plotters are faster and produce high density images. Plotters are used primarily in technical drawing and CAD (computer aided design) applications, where they have the advantage of working on very large paper sizes while maintaining high resolution.

Figure 3-19 A Plotter

3.2.5 Sound output device A speaker is an output device whose function is to output sounds when connected to a sound

card installed on the computer motherboard. Computer speakers range from a basic pair of speakers (stereo speakers) to surround sound speakers with the finest sound for computer gaming. Voice output systems are used in public places such as airports to signal passengers of events and they are efficient means for assisting physically challenged people.

3.2.6 Projectors The function of these devices is mainly to reproduce images or video frames on white screen. Some common types of projectors are video projectors, LCD projectors and handheld projectors.

Figure 3-20 LCD Projector

Video projectors accept a video signal as input, and the output is a corresponding picture frame on

a projection screen using a lens system. They are commonly used in conference room

presentations, classroom training as well as home cinema applications. LCD projectors, use liquid

crystal display technology to produce images. In the trend of projector development there is a

new craze of making it miniature. A pocket or handheld projector would enable projection of

images whenever and wherever desired. The idea is to incorporate projectors in mobile phones,

PDA’s (Personal Digital Assistant) and digital cameras.

3.3 Future of Input and Output Devices Given the current state of the art, computer input and output are quite asymmetric. The amount of information that is communicated from computer to user is typically far greater than that from user to computer.

Voice recognition software can be used as another means to supplement data input to the computer. A combination of voice, keyboard and mouse operations can be used for entering text information efficiently.

With the emergence of virtual reality, the computer input and output is becoming more like interacting with the real world. For input, this means attempting to make the user’s input actions as close as possible to the user’s thoughts that motivated those actions. Graphics, animations, audio, and other media can output large amounts of information rapidly.

3.4 Further readings

CANDELAND A.N., Guide to Computing Equipment: Vol. 2: Computing Peripherals,

Blackwell Publishers.

Multiple Choice Questions 1. A device that allows one to enter data into the computer in the form of text is:

(a) keyboard

(b) mouse

(c) printer

(d) modem

(e) scanner

2. A device used for producing multi-colour, high quality drawings such as architectural plans,

charts and maps is:

(a) laser printer

(b) plotter

(c) lightpen

(d) digitizing tablet

(e) touchscreen

3. In situations where carbon copies are needed and the quality is not too important, such as

invoice sheets, we use:

(a) fast plotter (b) laser printer (c) dot matrix printer (d) inkjet printer (e) photocopy machine

4. Resolution is not a relevant criterion for a:

(a) monitor

(b) digitiser

(c) printer

(d) scanner

(e) microphone

5. One advantage of the dot matrix printer over the laser printer is :

(a) Dot matrix printer produces higher quality output.

(b) Dot matrix printer prints more pages per minute.

(c) Dot matrix printer can print carbon copies.

(d) Dot matrix printer is portable.

(e) Dot matrix printer has higher running cost.

6. A device used for 3-D positional information in virtual reality systems is the:

(a) optical mouse

(b) split keyboard

(c) trackball

(d) data glove

(e) touchscreen

7. The choice of input device for an application such as tourism or public information system is:

(a) digitising tablet

(b) touchpad

(c) touchscreen

(d) keyboard

(e) mouse

8. Which of the following is not a true characteristic of LCDs?

(a) LCD screens are perfectly flat.

(b) LCDs have wide viewing angle.

(c) LCDs are light and take up less space.

(d) LCDs have low power consumption

(e) LCDs do not produce electromagnetic waves.

9. The number of colours that a video card can display is determined by

(a) dot pitch

(b) pixel density

(c) refresh rate

(d) power consumption

(e) bit depth

10. Which of the following device is least prone to input errors:

(a) keyboard

(b) touchscreen

(c) lightpen

(d) mouse

(e) touchpad

Exercises

Open-Ended Questions

1. Describe the characteristics of CRT monitor and the factors that affect its quality.

2. Differentiate between an impact printer and a non-impact printer.

3. Explain how a flatbed scanner works.

4. State two applications where touchscreen interface is used and outline the advantages of using

touchscreen.

5. Discuss the advantages and disadvantages of LCD and CRT monitors.

6. What are the factors you would consider before buying a printer?

7. Explain the importance and functionality of mechanical, optical and cordless mouse types.

8. Outline the merits and limitations of using touchpad and light-pen.

9. What is the difference between a plotter and a printer?

10. Discuss input and output systems that can assist physically challenged people.

Chapter 4

Secondary Storage

Learning Objectives Upon completion of this unit, you should be able to do the following: 1. Explain the need for secondary storage in computers. 2. Distinguish between secondary storage and primary storage method.

3. Identify various secondary storage devices.

4. Compare and contrast among various secondary storage devices available. 5. List the advantages and disadvantages of common secondary devices.

6. Select the most appropriate secondary device for storage purpose. 7. Explain briefly the operation of the Hard Disks, Floppy Disks and Optical Disks.

Overview A computer needs a storage space or medium to save its data either temporarily or permanently. This chapter will give an overview of the various ways that exist to store data permanently on

special devices which are often referred to as secondary storage devices. Students will have an overview of various commonly used secondary devices like hard disks, floppy disks and optical disks. Other devices like magnetic tapes and flash drives will also be described.

Secondary Storage

4.0 Introduction In Chapter 1, we saw that one component of computer hardware refers to storage devices. In fact

these devices can be further classified as primary and secondary storage devices. They are both

used to store information that need to be processed by the computer. However primary storage

devices (e.g. RAM) are only used as long as the computer is turned on. Once power goes off, all

information present in the RAM of the computer is lost (volatile memory).

Figure 4-1 Saving to a secondary device

Secondary storage devices on the other hand allow the permanent storage of information as long

as required by the user. For instance, you may want to save an assignment that you will edit or

print at a later time (Figure 4-1). Organizations may wish to keep records of their employees and

use these details to calculate salaries at the end of each month. With primary storage devices, the

user would have to enter the same information every time the computer is turned on. Imagine for

instance the disappointment that you will face if you need to re-enter the phone number of a

friend or relative each time you switch on your mobile phone and to lose it again when the phone

goes off! Fortunately this is not the case since in secondary storage devices, the information

stored is non-volatile, i.e., information stored is still present even if power is turned off. Also

most secondary devices will provide a number of benefits, some of which are:

Portability: information can be saved and transported to another location or computer

Security: sensitive information can be copied (backups) and kept in safe places

High capacity: secondary devices store practically most operating systems now and other

bulky applications software.

Space: large volume of electronic information can be stored easily alleviating space required for huge filing cabinets in organizations to store paper works.

This chapter will further help you in better understanding the concept of secondary storage devices as they are used in computers.

4.1 Different types of secondary storage devices There exists different types of secondary storage devices, each of them suitable for a different purpose. They mainly differ in the following aspects:

Technology used to store data

Capacity of data they can hold

Size of storage device

Portability of storage device and

Access time to stored data.

Currently the most common forms of secondary storage device are:

Floppy disks

Hard disks

Optical Disks

Magnetic Tapes.

Solid State Devices

Understanding the characteristics of each of them would help you choose the most appropriate

storage device to hold your data.

4.2 Floppy Disks Floppy disks often referred to as diskettes have been and are still being widely used to store

data of small size.

Figure 4-2 Floppy disks

They are very easy to use and are portable. They consist of a flat Mylar plastic disk that rotates within a hard plastic casing. Data is stored as electromagnetic charges on a metal oxide film

coating the Mylar plastic. Floppy disks also contain a write protect notch that can prevent writing to the disks. There exist several types of floppy disks but the most common one is the 3.5 inch floppy that can store data up to a capacity of 1.44 megabytes, something like 400 typewritten pages. A floppy drive is required to access a floppy disk.

Figure 4-3 Floppy drive

When the floppy is inserted in the floppy drive, the sliding metal shutter is opened exposing the

Mylar plastic and a read-write head moves across the exposed disk to either store or retrieve data. Data is recorded on the disk in closed concentric circles known as tracks.

Figure 4-4 Tracks in floppy disks

Often you will hear of the term formatting. This is nothing more than creating these tracks so

that your computer can save data properly on these disks. In other cases, formatting also refers

to completely removing all contents present inside the floppy. At the time when the computer

was first introduced, most documents contained only textual data and hence much information

could be saved inside floppy disks. Recently multimedia files (images, sounds and texts), which

are quite bulky in size, are becoming more and more popular and may require more than the

1.44Mbytes that a floppy may provide. This is why floppy disks are today only suitable for

limited purposes. Some manufacturers are already anticipating the need for higher capacity

floppy disks and are thus coming up with floppy disks cartridges that will use the same

principle as standard floppy disks but providing for higher storage capacities. Some examples

include Zip disks, Superdisk and (HIgh Capacity Floppy Disk) HIFD disk.

Table 4-1 Floppy disks capacities

4.3 Hard Disks Hard disks differ from floppy disk in that they have been designed to store very high volume of

data. Currently hard disks can store gigabytes of data (e.g. 200GB) and they are an integral part of the computer. Most operating systems are stored in hard disks and all materials (application software, documents, images, music files etc) that you save on your computer is stored in the hard disk.

Figure 4-5 Locating hard disk inside a computer

Locating the (logical) hard disk of a computer is very easy and all you have to do is to double click on the “My computer” icon that you see on the start up (desktop) screen of your computer. You

should get a window similar to the one shown in Figure 4-5. In contrast to floppy disks, data is stored on a metal platter in the form of magnetic spots. The metal platter is sealed inside a disk drive that protects the platter and as well enables reading and writing to the disk. Sometimes some hard disk may fail due to a head crash, resulting in loss of data and this is due to various reasons such as: improper handling of hard disks, voltage surge, malfunctioning of read/write head and more.

Figure 4-6 The inside of a typical hard disk

Similar to floppy disks, data is stored in closed concentric circles called tracks on the platters and a

hard disk may contain several platters forming hard disk packs that increase the capacity of data that can be stored by the device.

Figure 4-7 Inside hard disk pack

An interesting feature about hard disks apart from their large data holding capacity is their access time. Hard disks provide fast access both for reading and writing. That is why, it is always faster to open a document present on a hard disk rather than on a floppy.

4.4 Optical Disks Music CDs (compact disks) form part of a category of storage devices called optical disks. The latter make use of light energy to store information and are very suitable to store information of relatively high capacity (700MB).

Figure 4-8 A Compact Disk

They come in the form of a thin plastic disk, with a printed label layer on one side and a reflective layer (Figure 4.9) on the other side onto which a high laser beam will read or write data depending on the type of optical disk being used. Computer systems usually have access to these storage media via CD drives that contain a special lens to read and/or write data on the disks.

Figure 4-9 CD Drive

An interesting characteristic about CD drives is the speed of rotation. Typical speeds range from 12X to 52X. Actually the rotating speed determines the rate at which data is transferred from the computer to the disk and vice versa. A 32X drive will transfer 4.8 MB of data per second compared

to 3.6MB of data transfer per second for a 24X drive. The faster the drive therefore, the faster data can be read from the CD and used by the computer. Currently there exist three basic types of CDs that you will surely make much use of: CD-ROM, CD-R, and CD-RW. Basically all of them have

the same storage capacity except that they differ from their read-write capability.

4.4.1 CD-ROM CD-ROM stands for compact disk read-only memory. They are like commercially available music CDs that allows you to only listen (read) to music without altering the contents of the CD. They are used mostly for selling of music, movies and also for distribution of software packages like Microsoft Office.

4.4.2 CD-R CD-R stands for CD-Recordable that can be written on only once. These are special optical disks that typically come with no data at all in them such that a user can choose to add whatever contents he/she may wish to. Some example applications include creating a back up of your hard disk, creating your own music CD or saving your family album. To do so however, you will need a special CD-RW (read write) drive and appropriate CD burning software.

Figure 4-10 portion of disk that has got data written on it

4.4.3 CD-RW Also known as erasable disks, CR-RW (rewritable) can be used to save data several times. Their reflective layer is made up of a special coating that is not permanently altered when data is saved onto them such that they can be erased to accommodate new data. This type of optical disk is particularly useful to save large files that need to be updated regularly. Here as well, special CD-RW drive and appropriate burning software is required.

4.4.4 DVD DVD stands for Digital Versatile Disk or Digital Video Disk. They are now commonly used for the

distribution of movies since they offer high capacity storage medium with good quality. DVD and

CD are very similar in that both make use of light energy to read or write data on their reflective surfaces. However the technology behind DVD allows larger amount of data to be stored compared to CD (4.7-17 Gigabytes of data). Here as well, you will need a special DVD drive for your computer to access the data present inside a DVD.

Figure 4-11 The DVD trademark

Like CDs, there are three basic types of DVDs.

DVD-ROMs are commercially available DVDs for which the contents cannot be altered. For

example, movies are available on DVDs.

DVD-R comes initially as blank DVDs that allow the user to write only once though any

useful data, he/she may wish to save. Here as well special DVD-RW drive is required with

appropriate DVD burning software.

DVD + RW are very similar to CD-RW as they allow the user to save and erase the disk

several times. With the decrease in cost and availability of DVD–RW drives in most

computers, these high capacity disks will surely represent a safe and efficient means of

saving data.

Figure 4-12 Reflective surface of a DVD

4.4.5 CD/DVD Care CDs and DVDs need special care in order to ensure that any data saved on them is not lost, just like floppy disks. Some guidelines are as follows:

Do not expose your CD/DVD to extreme temperature.

Store them in their casing – any scratch makes it difficult to read through the reflective

coating.

Avoid touching the surface of the CD/DVD.

Do not write on the reflective coating of the CD/DVD and use only recommended marker

for any labelling on the label side.

Clean the CD/DVD with a soft cloth in an outward direction from the centre of the disk

avoiding circular movements.

4.5 Other secondary storage devices So far we have seen three common examples of secondary storage devices; floppy disks, hard disks and optical disks. All of them form an integral part of all microcomputers today. They satisfy most of user’s need although in some cases, additional devices are required. Two such examples are magnetic tapes and solid-state storage devices.

4.5.1 Magnetic tapes These have existed for a long time now. They are very similar to the tapes that are used in radio cassette player and video recorders and can still be found in video camcorders.

Figure 4-13 A magnetic tape

Magnetic tapes provide a very effective means for back up purposes of large amount of data (5

Gigabytes). However the main limitation is that data stored is in a sequential mode, that is, you may have to wait for several inches of tape to play before you can reach the data that is of interest to you. Consequently access to the required data is slow. Direct access on the other hand allows the user to go directly to the piece of information without having to wait for

any prior information to be accessed. A clear example of direct access is when you want to play a track on a music CD and that you only need to select the song you want to listen to. Magnetic tape cartridges or streamers are used mainly by micro computers whereas magnetic tape reels which offer much higher back up capacity are used by mainframes.

Figure 4-14 A magnetic tape reel

4.5.2 Solid state storage devices Unlike other storage devices discussed so far, solid state storage devices have got no moving parts and data is stored and retrieved from them in a similar manner as it would be from computer

memory. They come in different forms and sometimes under different commercial names such as USB disk, Pen drives, Flash disks etc. Some manufacturers tend to market these devices by adding components such as mp3 players within the devices and so on. However all of them work with very little power and represent a reliable device having relatively good storage capacity.

Typical storage capacity ranges from 32Mb to 1GB.

Figure 4-15 Typical solid-state storage device

4.6 Further readings

O’Leary T, O’Leary L., “Computing Essentials”, complete edition, McGraw-Hill, 2004.

Capron H.L., Johnson J.A., “Computers, Tools for an information age” eighth edition, Prentice Hall, 2004.

Exercises

Multiple Choice Questions 1. Which of the following is not a secondary storage device?

(a) Pen-drive

(b) Internal hard disk

(c) Magnetic reels

(d) Floppy disk

(e) Random Access Memory (RAM)

2. Which criteria help to differentiate between different storage devices?

(a) Portability

(b) Price

(c) Technology used

(d) Size

(e) All of the above

3. Data is stored on ________ in a hard disk

(a) Disk

(b) Tracks

(c) Metal platters

(d) Magnetic spots

(e) Stacks

4. ________ is more appropriate to store a 600MB file that needs frequent updating.

(a) CD-RW

(b) CD-R

(c) CD-ROM

(d) DVD ROM

(e) Floppy disk

5. Which one of the following lists the components in increasing storage capacity?

(a) ZIP disk, floppy, CD-ROM, Hard disk

(b) Floppy, hard disk, CD-R, Magnetic tape

(c) Magnetic tape, hard disk, floppy, CD-R

(d) ZIP disk, Hard disk, floppy, DVD

(e) Floppy, CD-R, DVD, Hard disk.

6. Which of the following is true for CDs and DVDs?

(a) CDs store more data than DVDs

(b) CDs store less data than DVDs

(c) CDs cannot be read by DVD drives

(d) They use the same technology based on magnetic fields.

(e) DVDs can be read by CD drives

7. The unit that is used to specify hard disk capacity is

(a) Bite

(b) Kg

(c) 1.44MB

(d) 42X

(e) GB

8. Secondary storage devices store data

(a) Temporarily when power is not available

(b) Permanently as long as power is available

(c) Permanently even if power is not available

(d) Temporarily as long as power is available.

(e) None of the above

9. Which of the following does an Optical disk use to read and write data?

(a) Magnetic read/write head

(b) Laser beam

(c) Magnetic spots

(d) Sectors

(e) Tracks

10. USB, pen drives and flash drives

(a) Have similar storage capacity like a floppy

(b) Can store less data than a standard floppy

(c) All mean the same device that can store lesser data than a standard floppy

(d) All mean the same device that can store more data than a standard floppy

(e) Are different storage devices that can store more data than a standard floppy

Exercises

Open Ended Questions 1. Distinguish between primary storage and secondary storage devices.

2. List and describe the most commonly used secondary storage devices in a personal

computer. 3. Why would a floppy disk not be appropriate to store a movie file? Explain your answer and

propose an alternative storage device. 4. Discuss the different types of hard disks. 5. What are the most common optical disks available on the market? Give a short description for each of them

6. Explain the acronyms R and RW in CR-R and CD-RW. 7. Explain the concept behind magnetic storage and optical storage. 8. List some rules for taking care of a floppy disk and an optical disk.

9. Where would a magnetic tape drive be suitable to use? 10. What is a flash drive and compare it with other storage devices like hard disks, floppy disks and optical disks.

Chapter 5

Programming

Learning Objectives Upon completion of this unit, you should be able to do the following: 1. Explain what programming and programming languages are. 2. Identify the different generations of programming languages.

3. Describe the evolution of common characteristics of, and differences among, programming languages.

4. Identify the six steps of programming. 5. Understand program analysis, design and coding.

6. Identify the different techniques of debugging. 7. Describe the importance of documentation and maintenance.

Overview This chapter introduces students to the fundamental concepts and terminology of computer programming and software development. The chapter assumes no programming background and

provides an overview of the software development process in addition to introducing important programming practices and methodologies. The chapter covers the following topics:

1. What is a program and what is programming?

2. The six main steps of the programming process which the programmer has to follow in order to

develop good programs that will solve real-life problems.

3. The generations of programming languages where the evolution of the different programming

languages are discussed,

4. Moreover, useful programming practices such as flowcharts, pseudocodes, object-oriented

programming will be introduced.

Programming

5.0 Introduction This chapter introduces the fundamental concepts of computer programming and discusses how programming is used as a tool for problem solving. Often, computer programming is perceived as mystical to students who are beginners to computer discipline, or who are of non-computer-related

disciplines. It is a great challenge for students to comprehend the process of writing a computer program. Writing software, computer programs, is a lot like writing down the steps it takes to do something.

5.1 Definition of a Program A program is a set of step-by-step instructions that directs the computer to do the tasks you want it to do and produce the results you want. A set of rules that provides a way of telling a computer

what operations to perform is called a programming language. There is not, however, just one programming language; there are many.

You are already familiar with some types of programs. As will be discussed in Chapter 7application programs are widely used to accomplish a variety of different types of tasks. For example, we use word processors to create documents and spreadsheets to analyze data. System programs as will be discussed in Chapter 6, on the other hand, focus on tasks necessary to keep the computer running smoothly.

Nowadays computer programs are incorporated in an ever increasing number of artefacts. It is

therefore self-evident that the program must be reliable. Good design plays a very important role

in assuring error-free program that meets its specifications.

5.2 What is Programming? Programming is the art of making a computer do what you want it to do. At the very simplest level it consists of issuing a sequence of commands to a computer to achieve an objective. In general, the programmer's job is to convert problems’ solutions into instructions for the computer. That is, the programmer prepares the instructions of a computer program and runs

those instructions on the computer, tests the program to see if it is working properly, and makes corrections to the program. The programmer also writes a report on the program. These activities are all done for the purpose of helping a user fulfils a need, such as paying employees, billing customers, or admitting students to college.

5.3 The Programming Process Developing a program involves steps similar to any problem-solving task. The programming process, also known as software development, consists of six main steps which are as follows.

1. Program specification: The program’s objectives, outputs, inputs, and processing

requirements are determined.

2. Program design: A solution is created using programming techniques such as

pseudocode, and flowcharts.

3. Program code: The program is written or coded using a programming language.

4. Program test: The program is tested or debugged by looking for syntax and logic errors.

5. Program documentation: Documentation is an ongoing process throughout the

programming process. This phase focuses on formalizing the writing description and

processes used in the program.

6. Program maintenance: Completed programs are periodically reviewed to evaluate their

accuracy, efficiency, standardisation, and ease of use. Changes are made to the program’s

code as and when needed.

7. 5.3.1 Step 1: Program Specification Program specification is also known as Program definition or Program analysis. In this phase the programmer has to determine the objectives of the program, the outputs of

the program, the inputs to the program, and the processing requirements to convert the inputs to the outputs. The program specification defines five tasks:

8. Program Objectives

Given a programming problem, one needs to determine exactly what the objectives of the

program to be developed are. Therefore a clear statement of the problem to be solved is

made. An example would be “A program to calculate and display the total marks of a

student for a given module”.

9. Desired Output

It is always better to determine the outputs of a program before the inputs. Specifying the

outputs refers to listing everything that is to be produced by the program. The user of the

program can sketch or write how the output should look. The output might be displayed on

the monitor or printed out on paper. For example the display to be produced by the

program might look as shown in Figure 5-1.

10.

Figure 5-1 Output display

11. 12. Input Data

Once the output is specified, the input data can be determined. For example, in the

program to display the total marks of a student, the coursework marks and the exam

marks should be provided.

13. Processing Requirements

Here the tasks required to convert the input data into output are defined. In the example

above, one processing step will be to add the coursework marks and exam marks in order

to have the total marks.

14. The Documentation

Ongoing documentation is highly recommended. At the end of this phase a Program's

Specification Document defining the program objectives, desired outputs, needed

inputs, and required processing can be very helpful.

5.3.2 Step 2: Program Design In the program-design step, a solution to the computer problem is planned using structured

programming techniques. Two common ways of planning the solution to a problem are to draw a flowchart and to write pseudocode, or possibly both.

Flowchart

Essentially, a flowchart is a graphical representation of a step-by-step solution to a problem. It

consists of arrows representing the direction the program takes, and boxes and other symbols

representing actions. It is a map of what a program is going to do and how it is going to do it. The

American National Standards Institute (ANSI) has developed a standard set of flowchart symbols.

Note that a computer does more than arithmetic. It also makes comparisons, for example,

whether something is greater than or less than, equal to or not equal to something else. Figure 5-

2 is an example of a flowchart.

Figure 5-2 Example of a Flowchart

Pseudocode

Pseudocode is an English-like non-standard language that lets you state your solution with more

precision than you can in plain English but with less precision than is required when using a formal

programming language as illustrated in Figure 5-3. Pseudocode permits you to focus on the

program logic without having to be concerned about the precise rules of a particular programming

language. However, pseudocode is not executable on the computer.

Figure 5-3 Example of Pseudocode

In the program design stage a solution is planned, preferably using structured programming

techniques. The best way to link the various parts of a flowchart is a combination of three logic

structures called sequence, selection, and loop. These structures enable the writing of

structured programs, which take much of the guesswork out of programming.

Sequences In the sequence structure, one program statement follows another. Here the program flows from one step to the next in strict sequence as shown in Figure 5-4.

Figure 5-4 Sequence of instructions

Selection The selection structure occurs when a decision must be made. This structure is also known as IF-THEN-ELSE because this is how one can formulate the decision.

Figure 5-5 Selection logic Structure

In Figure 5-5 the program reaches a decision point and if the result of the test is true then the program performs the instructions in Path 1, and if false it performs the actions in Path 2. This is also known as a conditional construct because the program flow is dependent on the result of a test condition.

Loops The loop structure describes a process that may be repeated as long as a certain condition

remains true. The structure is called a “loop” or iteration” because the program loops around (iterates or repeats) again and again.

Figure 5-6 Loop Structure

In this construct, as shown in Figure 5-6, the program steps are repeated continuously until some

test condition is reached, at which point control then flows past the loop into the next piece of

program logic.

5.3.3 Step 3: Program Code Writing the program is called coding. The next step in the programming process is to code the program – that is, to express the solution that has been planned in the program design step in a programming language. That is the logic from the flowchart or pseudocode will be translated to a

programming language. A programming language uses a collection of symbols, words, and phrases that instruct a computer to perform specific operations. There are many programming languages: Pascal, FORTRAN, C, and Java are some examples. The different types of languages will be discussed in detail later in this chapter.

Although programming languages operate grammatically, somewhat like the English language,

they are much more precise. To get a computer program to work, one has to follow exactly the

rules, the syntax, of the language being used. Of course, using the language correctly is no

guarantee that the program will work, any more than speaking grammatically correct English

means you know what you are talking about. The point is that correct use of the language is the

required first step. The program will be keyed as it is it composed, using a terminal or personal

computer. Programmers usually use a text editor, which is somewhat like a word processing

program, to create a file that contains the program. However, as a beginner, you will probably

want to write your program code on paper first.

5.3.4 Step 4: Program Test

In theory, a well-designed program can be written correctly the first time. However, newly written

programs will probably have a few errors. Therefore, after coding the program, one must prepare to test it on the computer. Debugging is a programmer's word for testing and then eliminating errors ("getting the bugs out").

It means running the program on a computer and then fixing the parts that do not work. Programming errors are of two types: syntax errors and logic errors.

Syntax errors

A syntax error is a violation of the rules of the programming language. For example, in C++,

each statement must end with a semicolon (;). If it is omitted, the program will not run due to a

syntax error. The compiler automatically detects syntax errors at the translation time. Modern

compilers detect syntax errors and indicate their possible locations within the program. The

programmer thus debugs the syntax errors without too much effort.

Logic errors

A logic error occurs when the programmer uses an incorrect calculation procedure. The compiler

cannot detect logic errors, hence the latter are more difficult to debug. There are several testing

steps for detecting logic errors.

The Testing Process

Several methods have been devised for finding and removing both types of errors, as follows:

Desk checking: When doing desk checking, a programmer sits at a desk and checks a printout of

the program. The programmer goes through the listing line by line looking for syntax and logic

errors. However it is much easier to detect all syntax errors at translation time.

Manual testing with sample data: Both correct and incorrect data are run through the program

manually, to test for processing results. The program should produce some expected results. If

this is not the case, then there is something wrong in the code.

Testing sample data on the computer: After all syntax errors have been corrected, the

program is tested for logic errors. Sample data are used to test the correct execution of each

program statement.

Testing by a selected group of potential users: This is sometimes called beta testing. It is

usually the final step in testing a program. Potential users try out the program and provide

feedback.

5.3.5 Step 5: Program Documentation Documentation consists of written descriptions and procedures about a program and how to use it. It is not something done only at the end of the programming process. Documentation is carried on throughout all the programming steps. This documentation is typically within the program itself and in printed documents. In this step, all the prior documentation are reviewed and finalized.

Documentation is a detailed written description of the programming cycle and specific facts about

the program. Typical program documentation materials include:

the origin and nature of the problem,

a brief narrative description of the program,

logic tools such as flowcharts and pseudocode,

data-record descriptions,

program listings, and

testing results.

Comments in the program itself are also considered an essential part of documentation.

Documentation is important for people who may be involved with the program in the future. These

people may include the following:

Users

Users need to know how to use the software. Some organizations may offer training courses to

guide users through the program. However, other organizations may expect users to learn a

package just from the written documentation. Two examples of this sort of documentation are the

manuals that accompany the software and the help option within most microcomputer

applications.

Operators

Documentation must be provided for computer operators. For instance, if the program sends them

error messages, they need to know what to do about them.

Programmers

As time passes, even the creator of the original program may not remember much about it. Other

programmers wishing to update and modify it (that is, perform program maintenance) may find

themselves frustrated without adequate documentation. This kind of documentation should include

text and program flowcharts, program listings, and sample output. It might also include system

flowcharts to show how the particular program relates to other programs within an information

system.

5.3.6 Step 6: Program Maintenance The last step in the programming process is program maintenance. The purpose of program

maintenance is to ensure that a program is free from errors and is functioning efficiently, and effectively. Activities in this area fall into two categories: operations and changing needs.

Operations

Operations activities concern locating and correcting operational errors, making programs easier to

use, and standardizing software using structured programming techniques. For properly designed

programs these activities should be minimal.

Changing Needs

During the lifecycle of a program, changes are unavoidable. All organizations change over time,

and their programs must also change accordingly. Programs need to be adjusted for many reasons

e.g. change in information needs, change in business rules and change in government policies.

It is important to note that a large proportion of the cost of programming is spent in maintaining a

program.

5.3.7 Summary of the programming process

Step Primary Activity

1. Program specification Determine program objectives, desired output, required input,

and processing requirements

2. Program design Create a solution using structured programming techniques

3. Program code Select the most appropriate programming language and write or

code the program

4. Program test Perform tests to find and eliminate syntax and logic errors from

the program

5. Program documentation Write procedure for users, operators and programmers

6. Program maintenance Adjust for errors, inefficient or ineffective operations, nonstandard

code, and changes over time

Table 5-1 Summary of steps in the programming process

5.4 CASE and OOP Efficiency and productivity are key concerns in most industries. They are particularly important for software development. Two resources that help are CASE tools and object-oriented software development.

5.4.1 CASE Tools Professional programmers are constantly looking for ways to make their work easier, faster, and more reliable. Many such tools are being developed and used in the software industry. Such tools

include Computer-Aided Software Engineering (CASE) tools which provide some automation and assistance in program design, coding, and testing.

5.4.2 Object-Oriented Software Development Traditional systems development is a careful, step-by-step approach focusing on the procedures needed to complete a certain objective. Object-oriented software development focuses less on the procedures and more on defining the relationships between previously defined procedures or “objects”. Object-oriented programming (OOP) is a process by which a program is organized into objects. Each object contains both data and processing operations necessary to perform a task.

In the past, programs were developed as giant entities, from the first line of code to the last. This

has been compared to building a car from scratch. Object-oriented programming is like building a

car from prefabricated parts – carburettor, alternator, fenders, and so on. Object-oriented

programs use objects that are reusable, self-contained components. Programs built with these

objects assume that certain functions are the same. For example, many programs, from

spreadsheets to database managers, have an instruction that will sort lists of names in

alphabetical order. A programmer might use this object for alphabetizing in many other programs.

There is no need to invent this activity anew every time. C++ and Java are the most widely used

object-oriented programming languages.

5.5 Programming Languages There are several programming languages in common use today. Programming languages are classified in terms of levels or generations, ranging from “low” to “high”. Programming languages are called lower level when they are closer to the language the computer itself uses. The computer understands the 0s and 1s that make up bits and bytes. Programming languages are called higher

level when they are closer to the language humans use – that is, for English speakers, more like English. There are five levels of language, numbered 1 through 5 to correspond to levels, or

generations. In terms of ease of use and capabilities, each generation is an improvement over its predecessors. The five generations or levels of languages are:

a. machine language

b. assembly languages

c. procedural languages

d. problem-oriented languages

e. natural languages.

5.5.1 Machine Language: The First Generation This lowest level of programming language, machine language, represents data and program

instructions as 0s and 1s, binary digits corresponding to the on and off electrical states in the computer. This is really the only language the computer truly understands; all other languages must be translated to the machine language before execution.

When engineers designed and built the first computers, the only people who could program these

computers were the engineers themselves. This was a tedious job, even for the engineers, as the

language used to communicate with the computer was in terms of binary signals (machine

Language). To perform a simple task such as adding two numbers, the engineer had to enter a

series of binary codes.

5.5.2 Assembly Languages: The Second Generation The machine language was so cryptic that even the engineers faced difficulties remembering the different codes. Thus, the engineers came up with a symbolic Language, so that instead of

remembering binary codes, they only had to remember mnemonic (symbolic) codes. For example,

A for add, C for compare, MP for multiply, and STO for storing information in memory. It permits the use of names for memory locations instead of actual address numbers. The assembly languages were machine dependent. Thus a program written on one particular machine could not be executed on another make of computer. A translator, called an assembly program, was required to convert the assembly language program into machine language.

5.5.3 High-Level Procedural Languages: The Third Generation People are able to understand languages that are more like their own (e.g., English) than machine languages or assembly languages. These more English-like programming languages are called “high-level” languages. However, most people still require some training to use higher-level languages. This is particularly true of procedural languages. Procedural languages, also known as 3GLs (third generation languages), are designed to express the logic – the procedures – that can solve general problems. Procedural languages, then, are intended to solve general problems.

With the third generation, we advance to high-level languages, many of which are

consideredportable languages. That is, they can be run on more than one kind of computer –

they are “portable” from one machine to another. Like assembly languages, procedural languages

must be translated into machine language so that the computer processes them. Depending on the

language, this translation is performed by either a compiler or an interpreter.

Compiler and Interpreter

A program written in a high-level language must be translated into machine language before it can

be executed. The translation is either known as compilation or interpretation, depending on how it

is carried out. If compilers have to translate the entire program into machine language before

executing any of the instructions, interpreters, on the other hand, translate and execute a single

instruction, or small groups of instructions at a time.

A compiler or interpreter is itself a computer program that accepts a high-level program as input

data, and generates a corresponding machine-language program as output. The original high-level

program is called the source program, and the resulting machine-language program is called

the object program. Every high-level language must either have a compiler or an interpreter.

Examples of Third Generation Languages

COBOL, COmmon Business Oriented Language, was designed to write business programs.

FORTRAN, Formula Translation, was designed for scientists and mathematicians. It is

very useful for processing complex formulae.

BASIC, Beginners All-purpose Symbolic Instruction Codes, was designed to allow the

layman to write a computer program. It was meant to be as simple as possible. In fact

many institutions used to teach BASIC as the first programming language.

Pascal was originally developed by Niklaus Wirth in Zurich, Switzerland in the 1970's. It

was named after the French scientist Blaise Pascal. The purpose was to develop a

disciplined high-level language for teaching structured programming.

C is a general purpose, structured language like Pascal. Dennis Ritchie originally

developed C in 1970's at Bell Telephone Laboratories. It is useful for writing operating

systems, spreadsheet programs, database programs and some scientific applications.

Ada is named after Augusta Ada, the English Countess Ada de Lovelace who is regarded as

the first programmer. Because of its structured design, sections of a large program can be

written, compiled and tested separately, before the entire program is put together.

HTML which stands for HyperText Markup Language, is not strictly a programming

language like Pascal or C. It consists of statements or tags that are saved in document

files. Browsers interpret these HTML documents to display web pages and provide links to

other web pages or related audio, video, and graphic files.

C++ is one of the most popular object-oriented languages, which is an enhanced version

of the C language. C++ includes everything that is part of C and adds support for object-

oriented programming. In addition, C++ also contains many improvements and features

that make it a "better C," independent of object oriented programming.

Java is another object-oriented programming language. Java programs known

asapplets are widely used to enhance animation and other interesting features of web

pages. Unlike the programs written with other languages, a program written with Java can

run on any system e.g. Windows, Mac, or Unix.

5.5.4 Problem-Oriented Languages: The Fourth Generation Third generation languages are valuable, but they require training in programming. Many people wanting to write programs found it difficult to learn the syntax of third level languages. Problem-oriented languages, also known as 4GLs (fourth generation languages) and very high level languages, require little special training on the part of the user.

Problem-oriented Languages were designed to solve specific problems e.g. querying databases

and allowed the programmer to concentrate more on the problem rather than spending time

learning the complex syntax of the language. Some of these fourth-generation languages are

used for special applications as described below.

Query Languages enable users, who are not programmers, to use certain easily-

understandable commands to search and generate reports from a database. An example would

be the commands used by clerical officers to look for specific information on a personnel

database-like date of first appointment or job title.

Application Generators contain a number of modules, which are logically related program

statements that have been pre-programmed to accomplish specific tasks. An example would

be a module that calculates value-added tax (VAT) on products. The programmer can simply

state which task is needed for a particular application. The application generator creates the

program code by selecting the appropriate modules.

5.5.5 Natural Languages and Visual Programming Languages: The Fifth Generation As they have evolved through the generations, computer languages have become more humanlike. The fifth generation language refers to using natural languages, such as English, French or Japanese, to communicate with computers. These languages are still under development. They aim at providing people with a more natural interface to communicate with computers. Users, therefore, will not require special training for writing programs. Researchers also hope that natural languages will enable a computer to learn to "remember" information, as people do, and to improve upon it.

The standard definition of a fifth generation language (5GL) is a computer language that

incorporates the concepts of artificial intelligence to allow direct human communication.

Additionally, these languages would enable a computer to learn and to apply new information as

people do. Rather than coding by keying in specific commands, we would communicate more

directly to a computer using natural languages.

Generation Sample Statement

First: Machine 1111100100011100111110001000001100011100000011010011

Second: Assembly ADD 210(8, 13),02B(4, 7)

Third: Procedural if (marks >= 70) grade= ‘A’;

Fourth: Problem SELECT student FROM studentRecords WHERE marks > 40

Fifth: Natural and Visual If patient is dizzy, then check temperature and blood pressure.

Table 5-2 Summary of the five programming language generations

5.6 Further readings

PRESSMAN R.S., Software Engineering A Practitioner’s Approach, McGraw-Hill International

Edition.

SEBESTA R. W., Concepts of Programming Languages, Published by Addison-Wesley.

STROUSTRUP B., The C++ Programming Language, Third Edition, Pearson Education.

Exercises

Multiple Choice Questions

1. Which one of the following steps of software development process involves keying statements

into a computer?

(a) program specification

(b) program design

(c) program code

(d) program test

(e) program documentation

2. In which step of the programming process a solution is created using programming techniques

such as pseudocode and flowchart.

(a) program specification

(b) program design

(c) program code

(d) program test

(e) program documentation

3. Program specification is also called _________________.

(a) program definition

(b) program charting

(c) program coding

(d) program design

(e) program modeling

4. The omission of a semicolon at the end of a statement in C++ is an example of a ___________

error.

(a) loop

(b) direct

(c) calculation

(d) design

(e) syntax

5. Which one of the following is carried out throughout all the programming steps?

(a) Coding

(b) Design

(c) Beta testing

(d) Documentation

(e) Desk checking

6. How are languages that can run on more than one kind of computer called?

(a) machine languages

(b) portable languages

(c) assembly languages

(d) problem-oriented languages

(e) query languages

7. The structured programming technique that graphically presents the detailed steps needed to

solve a problem is known as:

(a) object-oriented programming

(b) pseudocode

(c) flowchart

(d) syntax

(e) desk checking

8. Which one of the following statements best explains beta testing?

(a) Testing tools are used by the programmer to identify logic errors.

(b) The programmer sits at a desk and checks a printout of the program.

(c) Both correct and incorrect data are run through the program manually by the programmer, to

test for processing results.

(d) The programmer uses sample data to test the correct execution of each program statement.

(e) Potential users try out the program and provide feedback.

9. In which step of the programming process are the objectives, outputs, inputs, and processing

requirements determined?

(a) program specification

(b) program design

(c) program code

(d) program test

(e) program maintenance

10. What is the purpose of the program maintenance step in the programming process?

(a) To code the program, that is, to express the solution in a programming language.

(b) To write descriptions and procedures about a program.

(c) To ensure that a program is free of errors and is operating efficiently, and effectively.

(d) To determine the objectives, the outputs, and the inputs of the program.

(e) To plan a solution to the computer problem using structured programming techniques.

Exercises

Open-Ended Questions 1. What are the six steps of programming? What part does coding play in program development?

2. Describe CASE tools and OOP. How does CASE assist programmers?

3. What is meant by “generation” in reference to programming languages? What is the difference between low-level and high-level languages?

4. What is the difference between a compiler and an interpreter? What role would these tools have in programming with natural languages? 5. Explain what occurs during the program specification step of program development. 6. Differentiate using appropriate examples between syntax and logic errors.

7. Several methods have been devised for finding and removing both syntax and logic errors. List and explain three such methods. 8. Discuss the importance of having appropriate documentation for a program. Who will be using the documentation and for what purpose?

9. Explain, using appropriate examples, the difference between assembly languages and high-level procedural languages. 10. Suppose you have to write a program to output the electricity bill for a consumer. (a) List the output data. (b) List the input data required. (c) Identify and explain the processes involved for producing the electricity bill.

Chapter 6

Systems

Software

Systems Software

6.0 Introduction To be able to use a computer, we need software – a computer without any software is like an empty shell and is totally useless. We can group software into two categories:

Systems Software

o This is software required to start the computer and do general household jobs like

copying files, renaming files, providing access to the networks and provide service to

applications software.

Applications Software

o This is software like Microsoft Word, Internet Explorer that allows the user of the

computer to do some specific tasks, word processing and surfing the web for example.

Systems Software can be considered as being a layer between the hardware and applications

programs.

Figure 6-1 Software Hierarchy

6.1 Systems Software Systems Software is a very generic term and under its umbrella, it regroups many different types

of software. They all have their different specificities and will be responsible for different operations in the computer. The different software are:

Operating System – the main part of systems software

BIOS

Drivers

Utilities and service programs

Compilers, translators and Database Management Systems

6.2 Operating System The OS (Operating System) is the most important component of the Systems software. All applications have to talk to it at some point – it needs to be present on all PCs. Two examples of commonly used Operating Systems are Windows XP and Linux. They are built

differently, look different but do the same thing – provide a nice interface to users and allow easy interaction between application programs and the hardware.

6.2.1 Components of the Operating System The OS is made up of several small parts but they are packaged together when delivered to customers. These components are: the kernel, a GUI (Graphical User Interface) and some utility programs.

6.2.1.1 The Kernel At the heart of the OS is the kernel. It is the first part of the OS that is loaded into main memory and stays there as long as the computer is running. It provides basic services to other parts of the OS but is specifically responsible for memory management, task/process management and disk management.

6.2.1.2 The GUI This is the “visible part” of the Operating System. It usually provides a nice interface for the user to interact with the computer. Interaction will involve clicking on icons to manage files and launch application programs like browsers.

6.2.1.3 Utility Programs The Operating Systems usually comes accompanied by small programs that do some specific

tasks. Most OS have a module that manages communication with the network, for example, allowing connection to the Internet, simple text editors and some hard disk maintenance utilities, for example, the defragmentor.

6.2.2 Functions of the Operating System The OS does many things at any time. Typically, more than one program will be running at the same time, for example, an mp3 music file is being played while an antivirus software is running. Yet, the computer has limited resources (fixed amount of memory and CPU, ...) and they must be shared between the different programs running. So the different tasks an OS has to do is:

Process management

Memory management

Disk management

I/O Management

Communications management

6.2.2.1 Process Management The computer is very often running many programs at the same time. However, most computers do not have more than one CPU (programs are made up of instructions which must be executed by the CPU – Fetch-Execute-Cycle). So what happens if, for example, someone is chatting on the web, listening to music and scanning his computer for viruses at the same time? The computer will have to share the CPU among the different programs requesting it. To do so, the computer will work with processes.

What is a process?

The OS won't deal directly with application programs but rather with processes. An application

program can be a process but a process needs not be an application program. A process might just

another small program that has been started by an application program – for example, Norton

antivirus might be a process but to check for updates to that software on the Internet, it has to

launch a communication module (for example, the dialup window that appears on a PC when

connecting to the internet) that will allow it to connect to the Internet. That communication

module is a process as well.

So only saying that the CPU manages application programs is incomplete.

However, we still have the same problem; there's one (or two) CPUs and many processes to

manage. The OS tries to solve this problem by sharing the CPU among the different processes

needing it. It uses what is known as scheduling algorithms to decide which process should be

allowed to use the CPU and for how long.

When there are many programs requesting the CPU, the OS will allocate a small amount of time to

each process and cycle between the processes until the process has been executed.

6.2.2.2 Memory (RAM) Management Like for the processor, memory is a limited resource that has to be carefully managed. For programs to be executed, they must be loaded into the RAM. However, the amount of RAM

available in any computer is limited and very often there are many programs that need to be executed at virtually the same time – so memory is shared among the different programs.

The problem arises when all the programs that need to be executed in parallel need more space

than is available in memory. (Any program occupies some space in memory). So the solution is to

store part of the program on the hard disk and bring it in memory only when it is going to be

executed by the computer. This technique is called virtual memory and is used in most modern

Operating Systems.

In Linux systems, part of the hard disk is reserved for virtual memory when the Operating System

is being installed on the system – this part is called swap space.

6.2.2.3 Disk Management The Operating System must also keep track of what is happening on the hard disk(s); all the programs installed on a computer need a place to stay and they reside on the hard disk.

The hard disk space is a very dynamic environment; it houses programs and files. The programs

are quite static but files are constantly being created (for example, creating a new Word

document), growing (adding a picture into that document), shrinking(removing some text from

that document), moving(from hard disk to memory) and being erased.

So the hard disk needs to find sufficient space to house files and take care of them while they are

shrinking and especially growing.

It is also common for the files to be arranged into a hierarchy – files will be placed into folders

(directories).

Another very important job of the OS is file protection. When many users are sharing the same

computer, their files will be stored on the same hard disk/s. So the OS must provide a way of ensuring that a user does not have access or rather has restricted access to the files of his/her colleague. The different types of access usually provided for a file are:

read access – when a file can only be read and cannot be modified

write access – when a file can read and modified as well

execute access – this applies to programs that can be executed (run)

6.2.2.4 Input/Output Management The OS also has to liaise with the multitude of peripheral devices (e.g. Mouse, keyboard, printer,...) connected to the computer. These different devices will send input and output to the computer. The Operating System will liase with these different devices through device drivers (some drivers are not integrated in the Operating Systems) and will use them to issue instructions to peripherals. The latter will then return some data or will be asking for some data (for example, it might be a

page to be printed). So the main job of the OS will be to work with queues of information.

Buffering

The computer is a high speed device and data is moving very very quickly from one side of the

motherboard to another. However, the peripheral devices we interact with, like a hard disk for

example, do not operate at such high speeds. So if data is sent to these devices at the (fast)

speed that the processor is operating, the (slow) hard disk will not be able to write the data that

fast and so will lose some information (if a big tap is filling a bucket having only a small hole at the

bottom to release the water, eventually the bucket will overflow – the same thing will happen with

our hard disk).

An alternative would be to slow down the processor so that the program does not output more

information than the hard disk would be able to cope with but this would be unacceptable.

So the solution that the OS provides is to have a temporary storage location called the buffer that

stores data temporarily to cope with the speed difference that exists between devices operating at

different speeds.

An improvement to having one buffer is to have two buffers. When we have only one buffer, we

can only read or write to it at any time. When two are available, we can do reading and writing

simultaneously, that is, read from one while data is being written to another.

Spooling

Spooling is an acronym for Simultaneous peripheral operations online and it is just another way of

viewing a buffer. More specifically, in spooling, we have a buffer for a device that can be shared by

many users.

For example, many different users might want to print different documents at the same time or a

user might want to print several document and launch them at the same time. The printer is

however quite slow and is able to print only one job at any time and so the other jobs must wait in

a queue. The printer will remove each of them from the queue as it is ready to print them.

This technique is quite useful as it helps to accommodate devices operating at different speeds.

The most common spooling is for printers but we also have mail spooling where mails awaiting

sending are stored in a temporary location and are sent only when a computer connects to the

Internet.

6.2.2.5 Communications Management

The time when computers existed in isolation is over. Computers are very often connected to each

other through networks and to the Internet as well. So OS need to provide a way to allow

computers to connect to other devices. The connection can be through a network card or a modem

and the job of the OS is to establish the connection, maintain the connection while information is

being transferred and then properly close the connection.

6.2.3 Types of Operating Systems There a few different possible categorizations for Operating Systems. One of the most common categorisation relates to the number of users and tasks it can support at any time.

Single User Single Tasking: refer to OS that can support only one user at a time and only one

program being run at any time. This is characteristic of old Operating Systems like MS-DOS.

Single User Multi Tasking: refer to OS that can support many programs running at a time but

allow only one user to use the system. An example is Windows 98; it will allow a user to listen to

music while burning a CD for example.

Multi User Multi Tasking: refer to OS that in addition to being multi tasking can support more

than one user working on the computer at any time. How is this possible? The users will connect to

the computer through a network and from there launch applications that are executed by the

computer. Examples would be Linux, Unix and Windows 2000 Server.

Other classifications are:

GUI – are they equipped with a Graphical User Interface or are they simply command line.

Most current OS are GUI.

RTOS – Real Time Operating Systems are OS found in industrial machines where tight

control on what is happening is crucial. It does not have a GUI. It is mostly concerned with

I/O management.

6.2.4 Examples of Operating Systems The world of personal computers is dominated by the Windows Operating System from Microsoft. Yet, it is not the only Operating System in existence, many computers are running Linux and MAC OS as well.

6.2.4.1 Microsoft Most personal computers around the world are running a version of the Windows Operating

System. Initially, Microsoft started with MSDOS, a command line Operating System. It was a single tasking OS developed for single user. In DOS, we had the famous C prompt “C:\>” where users would type in commands on a black screen. For some time, this was good but the whole set up was not at all user friendly. Eventually, after some time, an OS with a Graphical User Interface (GUI) was introduced by Microsoft bearing the name Windows. Windows 3.1 was one of the first versions released and it had very crude graphics

(compared to modern OS) but at that time, hardware was not powerful and it would have been hard to support elaborate graphics.

Eventually Microsoft moved to Windows 95 which was quite a revolution in terms of GUI and user friendliness – no more would the computer start to a black screen; now a nice graphical user interface would welcome the user. From then onwards, we have witnessed many changes being brought to the OS (but no revolution) and we have moved through Windows 98, Windows Millennium, Windows 2000 to eventually reach

Windows XP. The next release of Windows, initially code named Longhorn will eventually be released as Windows Vista.

Figure 6-2 Microsoft WindowsXP

6.2.4.2 Linux Linux is the alternative to Windows available for PCs and compared to Windows, it is free and Open-source meaning that anyone has access to the Linux source code and the latter can be freely modified. Linux was originally developed by a Linus Torvalds, at that time, a student at the University of

Helsinki and Linus is still responsible for the development of the Linux kernel, the central part of the Operating System. However, other companies have taken up the development of additional software that come with the kernel and these are bundled together and are known as the distributions of Linux. There are many several distributions available, most of them free, among which the most common are Red-Hat , Suse, Debian, Ubuntu, Mandrake,...

Linux is now used in many places:

Universities very often have labs where the PCs have only the Linux OS installed (no

Windows).

in Web servers – many big companies like Google have Linux running on their servers

Playstation 3 will come with a linux distribution pre-installed on it

Figure 6-3 Ubuntu Linux

6.2.4.3 Unix

Unix was originally developed between 1960 and 1970 at AT&T Bells lab by Thomson, Ritchie and

McIIroy. It was designed to be a portable and multiuser Operating System.

The original Unix Operating System is not in use anymore. What exists is a document that

specifies a set of guidelines that an Operating Systems should have to be called Unix compliant.

“The present owner of the UNIX trademark is The Open Group, while the present claimants on the

rights to the UNIX source code are The SCO Group and Novell.”

Many different variations exist like BSD Unix from Berkeley University, AIX from IBM and Solaris

from Sun.

Unix is rarely found on PCs, though it is going to work there. It is frequently used on Web servers

and machines for high-end computing.

6.2.4.4 Mac OS X Mac OS X is the latest Operating System released by Apple for Macintosh computers. Due to the MAC's different architecture (Apple has been using the Power PC architecture rather than the Intel

architecture), it could not run Windows and so has stayed Windows free up to now. But Apple has

now adopted the Intel architecture and we can now install Windows XP on Apple computers.

Figure 6-4 Mac OS X

6.3 The BIOS The BIOS stands for Basic Input Output System. It is found in the ROM of the computer and is the first piece of software that is run by the computer.

Figure 6-5 The BIOS

The Booting process

When the computer is powered on, the power supply is started. It will take some time for the

power to rise to a stable value and once it is done, the processor is started.

The first thing it will do is load the BIOS from the ROM. How does it know where to get the BIOS?

This is hard coded into the processor and the start address of the BIOS is always stored at the

same address in the ROM.

The BIOS will then carry out a series of tests to determine if the memory, processor, graphics card

and others are operating properly – Power On Self Test (POST Test). It usually emits a series of

beeps if something is not right.

After testing the different components, it will display a summary and then attempt to load the OS.

The BIOS will look for a device to boot from. A computer will normally boot from the hard disk but

that setting of the BIOS can be changed to allow booting to take place from a floppy disk or

CD/DVD Drive instead.

If the hard disk is the selected device data from track 0 and sector 0 from the hard disk is loaded

into the RAM – this is where the Master Boot Record (MBR) is stored. It will look at the same

address on a floppy disk or any other bootable media.

On finding that, the code in the MBR takes over and the Operating System is eventually loaded.

6.4 Drivers To be able to talk to the different peripherals like keyboard, printer, graphics card that are attached to a computer, the Operating System needs an interface. That interface is what is known as a device driver. That interface is needed because the processor and peripherals are built by different

manufacturers who use different standards and thus they do not inherently understand each other. In old Apple computers drivers were not needed because everything was manufactured by Apple; the printer, screen, … However in new PCs, this is not the case and we do need drivers.

Yet, most drivers for standard peripherals like the keyboard and mouse are now already available

in the Operating System and do not need to be installed. The new peripheral is simply connected

and it is immediately recognized – this is what is called Plug and Play.

6.5 Utilities and service programs

These are small programs that do some general house-keeping tasks. They take care of some

simple but yet essential tasks like formatting a diskette (erasing everything found on a diskette)

and defragmenting a hard disk. Normally these utilities will be come bundled with the Operating

System but some special software like Norton Utilities can also be used to do these.

6.6 Translators The computer understands only 0s and 1s. This is called the machine language. So when giving instructions to a computer, (when we are writing a program, we are basically giving the

computer a series of instructions to execute) we should talk to it in terms of 0s and 1s. However, humans are not very good at that and so we write programs in “High Level languages”

which resemble English. But having done so, we need to convert these instructions to 0s and 1s and this is where the translators come into play.

Basically, there are two types of translators:

Compilers

Interpreters

6.6.1 Compilers A compiler takes a whole program (source code) written in a High Level Language and converts

it into an Object code, which is basically machine code. The object code can then be processed

by a linker which will link the object code with some other object file to allow it to execute independently. If there are any errors during the compilation process, a list of errors are generated, else the program is available for the linker to make an executable file out of it.

6.6.2 Interpreters An Interpreter will convert each line of a program, as needed, into machine code form as it is being run. So the program will require the interpreter to be present on the machine at all times when it is going to be run.

Moreover, since each line is being converted to machine code as the program is being run, it usually takes longer to execute a program with an interpreter compared to compiling it in one go.

6.7 Further readings

TANENBAUM Andrew S., Modern Operating Systems, Prentice Hall

DISTROWATCH.COM, http://distrowatch.com/

Exercises

Multiple Choice Questions

1. Which of the following is NOT part of Systems Software?

(a) Operating Systems

(b) BIOS

(c) Compiler

(d) Microsoft Word

(e) Drivers

2. Which of the following is NOT an example of an Operating System?

(a) Suse Linux

(b) BSD UNIX

(c) Windows 95

(d) AVG Antivirus

(e) MS-DOS

3. Which type of Operating System allows several users to work at the same time and also allows

each user to have many applications open at the same time?

(a) Single user single tasking

(b) Single user multi tasking

(c) Multi user multi tasking

(d) All of the Above

(e) None of the above

4. When several people are launching printouts at the same time and a single printer is available,

a technique known as _________________ is used.

(a) Spooling

(b) Communication

(c) Buffering

(d) Single tasking

(e) Scheduling

5. Which function of the Operating System ensures that someone is not illegally manipulating a file

not belonging to him?

(a) Memory Management

(b) Disk Management

(c) I/O Management

(d) Communications Management

(e) Processor Management

6. How is part of the Hard Disk that is reserved for Virtual Memory called in Linux?

(a) Boot partition

(b) Virtual Hard Disk

(c) RAM

(d) Swap space

(e) MBR

7. Norton Utilities is an example of:

(a) Drivers

(b) Translators

(c) Utilities

(d) Operating Systems

(e) None of the above

8. The BIOS of the computer is stored in

(a) RAM

(b) ROM

(c) Hard Disk

(d) CD

(e) Floppy disk

9. The process of starting up a computer is known as

(a) POST Testing

(b) Translating

(c) Booting

(d) Loading

(e) Creating

10. A compiler translates a source program to:

(a) An object code

(b) An executable

(c) English

(d) A compressed file

(e) A linker

Exercises

Open-Ended Questions

1. What is the job of the BIOS in a computer?

2. The Linux Operating System is available under a lot of distributions. Name at least 10different

distributions.

3. Give five examples of utilities used in a computer.

4. Describe how processes are managed in an Operating System.

5. Give an example of an Operating System for each of the following:

a. Single user single tasking

b. Single user multi tasking

c. Multi user multi tasking

6. Describe the booting up process.

7. How do interpreters differ from compilers?

8. Explain the concept of Virtual Memory.

9. Compare and contrast the following Operating Systems:

a. Windows XP

b. Linux

c. MAC OS X

10. Give some examples of compilers and interpreters.

Chapter 7

Applications Software

Learning Objectives

Upon completion of this unit, you should be able to do the following:

1. Differentiate between customised and off-the-shelf application packages.

2. Know the salient features of common word processing packages.

3. Know the basic and analytical features of common spreadsheet packages.

4. Understand the importance of database packages and their basic features.

5. Demonstrate the capability to develop presentations using presentation packages.

6. Configure and use electronic mail packages.

7. Identify appropriate package to perform a task.

Overview Applications software is a subclass of computer software that employs the capabilities of a computer directly

to a task that the user wishes to perform. This should be contrasted with System Software which is involved

in managing a computer's various capabilities, but typically do not provide software that benefits tasks of

users. The term application refers to both the Application Software and its implementation.

This chapter introduces some typical examples of Application Software namely word processors, spreadsheets,

presentation graphics software, Database Management Systems, email packages and web browsers.

Applications Software

7.0 Introduction

Applications Software is a kind of computer software that employs the capabilities of a computer directly to a

task the user wishes to perform. This should be contrasted with Systems Software which is involved in

managing the computer's various capabilities (refer to Chapter 6).

There are two main types of Applications Software:

General purpose Applications Software handles tasks such as word processing, spreadsheets,

databases, graphics and integrated programs.

Special purpose Applications Software handles the specific needs of a particular profession or

business. For example, a company might use special purpose Applications Software such as a payroll

system to prepare payslips for its employees.

Multiple applications bundled together as a package are sometimes referred to as an Application Suite.

Examples are Microsoft Office and OpenOffice.org, which bundle together a word processor, a spreadsheet, and

several other discrete applications. The separate applications in a suite usually have user interfaces that have

some commonality making it easier for the user to learn and use each application. Often they may have some

capability to interact with each other in ways beneficial to the user. For example a spreadsheet might be

embedded in a word processor document even though it had been created in the separate spreadsheet

application.

7.1 Word Processing

A word processor is a computer application used for preparing documents for viewing and printing purposes. A

word processor helps the user in writing, modifying, formatting and printing of text.

The earliest versions of word processing applications solely focused on simple text processing tools. But with

the advancements made in the field of desktop publishing, it is very difficult to distinguish between word

processing and desktop publishing.Some of the features of a word processor are:

Annotation – This feature enables the users to add comments in certain sections of the document. It

enhances the edit and review process of the documents. The owner sends the document to the

reviewers who review it and in the process add annotations. They send it back to the owner who can

now make the required changes. The annotations can also be in the audio format.

Background –This feature allows the user to define the background layout for the document.

Borders and Shading – This feature allows the user to define borders for the page, paragraph or

sentence according to his / her requirement.

Bullets and Numbering – Using this feature the user can enable automatic numbering or bulletting

a set of sentences.

Font Case – this feature allows the user to change the case of the selected text. The user can change

the selected text to either uppercase, lowercase, sentence case, title case or toggle case.

Font Specification – This feature helps the user to change the font specifications of portions of text

within the document. The user can specify the appearance of the font like bold, font size and font

typeface.

Graphics – This feature enables the user to embed pictures from files and cliparts, and graphs from

spreadsheets. Many word processors come with an in-built drawing tool which enables users to create

line art in their documents and a Word Art tool which helps them in generating various forms of text.

Headers, Figuress and Page Numbering – This feature enables the users to place text that will

appear on all pages. Any text placed in a header or footer will automatically repeat itself when a new

page is added to that document. The word processor allows the automatic numbering of pages.

Language Translation – This feature enables users to translate text from one language to another.

Letter Assistant – Most word processors assist the users in creating letters through the use of

standard templates.

Macros – This feature enables the users to define macros which allow them to record a series of

actions and repeat these by invoking the macro name. A macro is a character or string which

represents a series of keystrokes or actions.

Mail Merge – This feature uses two input files, a data file and a form file and combines or merges

them to produce a single output file. It enables the generation of letters based on a template. For

example, an invitation letter may be sent to many people, whose names and addresses are

automatically retrieved from an address book. The power and flexibility of this feature varies from one

word processor to another.

Footnotes and cross-references – Automates the numbering and placement of footnotes and

enables you to easily cross-reference other sections of the document.

Page Layout – This feature allows the users to specify different margins in the document. It also

allows the users to define page sizes and page layouts. The word processor automatically adjusts the

text according to the layout.

Search and Replace – This feature allows the user to search for the occurrence of a word or phrase

and replace one or all occurrences with another word or phrase.

Spelling and Grammar Checker – This feature helps to detect typing errors and misspellings.

However, the semantics of a sentence cannot be verified. On completion of a sentence or a phrase

this feature checks for grammatical mistakes and provides suggestions to the users.

Speech Recognition – This feature enables the users to create documents by dictating the text.

Most of the current word processors support this feature.

Table of contents – This feature enables automatic construction of a table of contents for a

document.

Thesaurus – This feature enables the user to search for the synonyms (alternate words with the

same meaning) for a word the user wants in the document.

Print Preview – This feature enables the user to view the document in the print copy format. This

concept is referred to as ‘What You See Is What You Get’ (WYSIWYG).

Text Alignment and Line Spacing – This feature enables the user to change the alignment of the

text with reference to the margins. The text can be left aligned, right aligned; centre aligned; or

justified. It also provides facility of customizing the paragraph indentation and specifying the type of

tab stops. The facility of customizing the line spacing is also provided by the word processor. A user

can edit a document with single line spacing which is the default setting or double line spacing.

Text Manipulation – This feature allows the users to select a set of characters, cut, copy or paste

them in another location of the document. This helps the user to reorganize the text in the document.

Word Wrap – This feature ensures that the word processor automatically moves the cursor to the

next line when the margin of the page has been reached, and will readjust the text if the margins are

changed.

Among the open source word processing applications, Writer (www.openoffice.org), Jarte (www.jarte.com) and

AbiWord (www.abisource.com) are some of the popular applications.

Figure 7-1 Open Office Writer

Among the commercially available word processing applications, Microsoft Word and WordPerfect are some of

the well known applications.

Figure 7-2 Microsoft Word

7.2 Spreadsheets

A spreadsheet is a table of values arranged in rows and columns. Each value can have a predefined

relationship to the other values. If one value is changed, therefore, other values may need to be changed as

well.

Spreadsheet applications (sometimes referred to simply as spreadsheets) are computer programs that allow

the creation and manipulation of spreadsheets electronically. A spreadsheet program can be used to perform

calculations, analyse and present data. Spreadsheet programs include tools for organising, managing, sorting

and retrieving data and testing "what if" statements. The chart feature displays numerical data as a graph.

Examples of spreadsheet applications include Microsoft Excel, Lotus 1-2-3 and Quattro Pro. Microsoft Excel

is a spreadsheet program written and distributed by Microsoft for computers using the Microsoft Windows

Operating System. It features an intuitive interface and capable calculation and drawing tools which, along with

strong marketing, have made Microsoft Excel one of the most popular microcomputer applications to date. Not

too long ago, Lotus 1-2-3 was considered the "standard" spreadsheet. Microsoft Excel now holds that

distinction, with a clearly dominating market share.

The worksheet area of the spreadsheet has letters for column headings across the top, ranging from A

through Z and AA through IV (i.e. 256 columns). Furthermore it has numbers for row headings down on the

left side, ranging from 1 to 65536. The intersection of a row heading and a column heading is known as a cell.

The cell can hold a single unit of information and its position in the worksheet area is called a cell address.

The cell address is denoted by its column and row position e.g. C8 in Figure 7-3. The current cell address is

displayed in the address box. While working with a spreadsheet, the cell pointer points to the cell where data

is to be changed or entered. The selected cell is known as the active cell and the data entry bar shows the

data as it is being entered in the cell. The cell pointer can be moved using the tab, arrow keys or the mouse, in

the same way as in a word processor.

Figure 7-3 Overview of a Spreadsheet

7.2.1 Basic Features of a spreadsheet

Values – A number in a cell is known as a value and it may be used in mathematical calculations. The

type of data to be stored and displayed in each cell can be defined. For example, the value can be of

type text, number, currency or date. A value can be formatted to show decimal places, dollars (if the

type defined is currency) or percentage. An example of a value shown in Figure 7-3 is “$4.49”.

Labels – Labels are usually texts that are used as headings for columns. They are used to identify

information in a worksheet. In Figure 7-3, “PRICE” is a label. A label can be formatted in various

ways, for example, it can be made boldfaced and centered.

Formulae – Formulae are instructions for calculations. They compute results using the values in

referenced cells e.g. in the example shown in Figure 7-4, the cell F6 has the formula "=B6*C6"

(shown at the top of the Excel Sheet in Figure 7-4) which multiplies the content of B6 (i.e. 5.00) to

the contents of C6 (i.e. 6) to give 30.00 as displayed.

Figure 7-5 Sample data on a spreadsheet showing use of function

What-If analysis/Recalculation – This refers to changing one parameter in a calculation and

observing its effect on an overall calculation. In a spreadsheet, where formulae are used, one can

simply change the contents of the cells that are referred to in the formulae and the latter will

recalculate the value automatically. For example, changing the quantity sold for one item will result in

a change in the sales figure for that item and in turn causes a change in the total sales figure. By

manipulating the values, users can use spreadsheet formulae to explore different options.

Graphs and Charts – Graphs can be used to visualise the information found in spreadsheets. These

are used when people are not really interested in the actual values, but would like to have an overall

idea of the general trend. Many spreadsheets provide the option to present data into various types of

graphs namely bar-chart, pie-chart, column chart and so on. For example the following figure shows a

pie chart generated to show the quantity of each item sold in the pharmacy. Note that any change

made in the values in the worksheet will result in a corresponding change in the chart.

Figure 7-6 Pie-Chart generated using the sample data from Figure 7-4

Dynamic File Links - Some spreadsheet software offer the facility to dynamically link cells in one

worksheet file to cells in other worksheet files. Therefore if there are changes in one worksheet file,

linked cells in the other files are automatically updated.

7.3 Presentation Graphics Software

Presenting information in the form of graphics can help people grasp information more easily. Presentation

software (sometimes called "presentation graphics") is a category of application program used to create

sequences of words, graphics and visuals that tell a story or help support a speech or public presentation of

information. The software also includes functions for creating various types of charts and graphs and for

inserting text in a variety of fonts. Most systems enable import of data from a spreadsheet application to

create the charts and graphs.

Presentation software can be divided into Business Presentation Software and more general Multimedia

Authoring Tools, some products having characteristics of both. Business presentation software emphasizes

ease-of-learning and quickness-of-learning and use. Multimedia Authoring Software enables the creation of a

more sophisticated presentation that includes audio and video sequences. Business presentation software

usually allows images and sometimes audio and video developed with other tools to be included.

Some very popular presentation software, such as Microsoft PowerPoint, and Lotus Freelance Graphics are sold

stand-alone or can come as part of office-oriented suites or packages of software. Other popular products

include Adobe Persuasion, Astound, Asymetrix Compel, Corel Presentations and Harvard Graphics.

Figure 7-7 shows a slide from Microsoft PowerPoint, which includes some text, a table and a chart.

Figure 7-7 Sample slide from Microsoft PowerPoint

The software can be used to print transparency slides for use on overhead projectors and produce electronic

presentations (known as slide shows) by connecting the computer with an RGB projector. These are support

materials for both the speaker and the audience during a talk or presentation and the message passes more

easily. A slide can include text, sound, art and even movie clips. These tools greatly enhance the quality of

professional presentations.

Some Features of Presentation Graphics Software

Links – Links can be easily added to other slides within the presentation (thus allowing easy

navigation through the presentation slides), to other files, or to web pages (thus allowing access to

other files and the web within the presentation).

Slide Show Animation – Animation Schemes give users one-click access to professionally designed

animations. It is possible to control how and when text, graphics, and other objects appear on the

presentation slides. Animation can aid in focusing attention during a presentation and make the slide

show more interesting. Users can easily get a preview of each animation scheme and can try through

various options until they find the animation they want.

Slide Design – This feature gives users an easier way to discover their design options. The user can

choose among a selection of design templates. Design templates contain color schemes, slide and title

masters with custom formatting, and styled fonts, all designed to create a particular look.

Multimedia – Sounds/videos can be inserted as an integral part of a slide show as an object. This is

the most convenient method, but can make the file size very large - a minute of recorded sound can

require up to 10MB of disk capacity. A solution could be to save the whole file onto a CD or other large

memory storage media.

Recording a voice narration or sound in a slide show – Narration can be added to a one or more

slides. Users might want to add narration in the following cases:

- A Web-based presentation.

- For archiving a meeting so that presenters can review it later and hear comments made during the

presentation.

- For individuals who can't attend a presentation.

- For self-running slide shows.

Creating charts, tables and organizational charts – Charts and tables are usually created with

spreadsheets. They can then be easily inserted into the Presentation graphics software using the Copy

and Paste commands. However, simple charts and tables can be directly created in the presentation

graphics software – the advantage is that they will take on the colours and format of the current slide

design.

7.4 Database Management System (DBMS)

A database is a collection of data which is stored in an organised fashion so as to ensure that the data is easily

accessed by the application programs. A database can be thought of as an electronic filing system. A database

helps the user to store large amounts of information of various complexities. Thus a database is a collection of

information. Examples of collection of information include: Telephone numbers, Employee Details, Library Book

Details amongst others.

To access the information from a database, a user has to use the Database Management System (DBMS).

DBMS is a collection of computer applications which help the user to store, modify, extract and manage

structured data or information found in the database.

Thus a DBMS helps the user to organise and store the data as well as retrieve the required information and

print the reports according to the requirement.

Some of the examples of the scenarios where DBMS is used are accounting packages, management

information systems and customer support systems

Among the open source Database management systems Base (http://dba.openoffice.org) is well known.

Some of the well-known commercial Database Management Systems include Oracle, Sybase, Microsoft Access,

MySQL and SQL Server.

Figure 7-8 OpenOffice.org Base

Figure 7-9 Example of a Database Management System – Microsoft Access

Some components of a Database Management System are:

Table – This component takes care of storing the data. Each table is made up of rows called records

and columns called fields. In Figure 7-9, Employee and Department are examples of tables. Employee

table contains the fields Ecode, Ename, DOJ and DeptNo. The Department table contains the fields

DeptNo, Dname and MgrCode. Fields are discrete pieces of information and are made up of types of

data which ensures the correct type of information goes into the field. The field can be a text, an

autonumber, a number, a date, a memo, amongst others.

Form – This component enables the user to enter or manipulate data by providing user friendly

interfaces. It is easy for a user to enter data into the database using an interface as shown in Figure

7-10

Figure 7-10 Customised Interface to enter the employee details into the database.

Query – This component allows the user to write instructions for extracting specific information from

the table. The user can search for a particular piece of information by creating and executing the

queries. Figure 7-11 shows a query to retrieve the names of employees working in an Accounting

Department.

Figure 7-11 Queries in Microsoft Access

Report – This component enables the user to print customized reports based on the criteria specified.

Figure 7-12 shows an example of customized report.

Figure 7-12 A Report generated in Microsoft Access

In most scenarios, there are data or information that are related to each other. These types of data are stored

in a category of databases known as relational databases where the related data is organized in separate

tables. These tables are linked to each other by defining the relationships which help the user retrieve the

required information which is stored in several tables. Figure 7.13 shows the relationship between the

department table and employee table. Both the tables are linked with each other by a common field DeptNo

which know as the Key Attribute.

Figure 7-13 Relationship between Department and Employee Table in Microsoft Access

Amongst the other features, Database Management Systems provide the facility for sorting the data in the

database, performing mathematical calculations and restricting access to the data.

7.5 Electronic Mail Packages

Electronic mail, abbreviated e-mail or email, is a method of composing, sending, and receiving messages over

electronic communication systems.

The term e-mail applies both to the Internet e-mail system based on the Simple Mail Transfer Protocol (SMTP)

and to intranet systems allowing users within one company or organization to send messages to each other.

To receive an elesctronic mail, the user must have a mailbox, a storage area, usually on the mail server which

holds the email messages until the user has time to read them. Each mailbox has an address which is the

user’s email address. In addition, the computer used to read and send emails must have some email software.

To be able to access his emails, a user must provide his username and password. There are a number of email

applications available and Table 7-1 gives a list of some of the most common ones.

Table 7-1 Example of Email Applications

Figure 7-14 gives an illustration of an email application.

Figure 7-14 Example of email package – Microsoft Outlook

Some common features of email packages are:

Creating a new email by clicking on the New button as shown above. Sending the mail as To, Cc or Bcc.

- Cc is an abbreviation for carbon copy. If you add a recipient's email address to this box in a

message, a copy of the message is sent to that recipient, and the recipient's email address is visible

to other recipients of the message.

- Bcc is an abbreviation for blind carbon copy. If you add a recipient's email address to this box in a

message, a copy of the message is sent to that recipient, and the recipient's email address is not

visible to other recipients of the message. If the Bcc box isn't visible when you create a new message,

you can add it.

Attaching a file to the message – to send some other documents, like a word document, a PowerPoint

presentation, photos etc

The above-mentioned features are illustrated in Figure 7-15.

Figure 7-15 Common features of email packages

Attaching an email signature to an email

A user can create an email signature (Figure 7-16) by clicking on Options in the new message as

shown in Figure 7-15. Once the user has created such a signature, it will be automatically added to

all new messages as shown above.

Figure 7-16 Creating an email signature

Address Book

The address book can be used to keep a list of all contacts and their email addresses. When the user

clicks on either To, Cc or Bcc, he has access to the address book. He simply selects a user from the

list and clicks on either To, Cc or Bcc to select the email receiver and how the email will be sent.

Figure 7-17 illustrates this.

Figure 7-17 Choosing an email address from the address book

7.6 Web Browsers

A web browser is a software application that enables a user to view and interact with text, images, and other

information typically located on a web page at a website on the World Wide Web or a local area network.

Figure 7-18 A closer look at the Google Toolbar

7.6.1 Features of Browsers Different browsers support different features and the most common ones are:

support of a variety of web languages

support of various graphical format (for images) including GIF, PNG, JPEG and SVG

Cookies

Digital Certificates

Bookmarks – can keep the URL of useful websites

History – list of previously visited URLs (the user has the option to specify the period of time for which he

wants the history)

Caching of web contents – when the user first accesses a page from a website, a copy of the page is kept

locally. The next time he wants access to that web page, the page will be accessed from the cache instead

of accessing the website again.

Support various kinds of media through the use of plug-ins such as Flash player and Quicktime

Pop-up advert blocker

Exercises

Multiple Choice Questions 1. Which of the following formats will draw a line through selected text?

(a) Subscript

(b) Underline

(c) Outline

(d) Strikethrough

(e) Superscript

2. To create an Outline style numbered list, which of the following dialog boxes would you use?

(a) The Numbering dialog box

(b) The Outline Numbered dialog box

(c) The Bullets and Numbering dialog box

(d) The format dialog box

(e) You do not use a dialog box to create an Outline style numbered list, you would use a Toolbar

button

3. When a word is to be inserted into the middle of an existing paragraph, the user has to

I. Click to position the cursor of the insertion point where you would like to type the word

II. Select the paragraph that you would like to insert a word into

III. Do nothing, Word will automatically insert the word where you want it

(a) I only

(b) II only

(c) III only

(d) I & II

(e) I, II & III

4. In order to modify a page number, you must activate which of the following areas of your document?

(a) The Header or Footer Area

(b) The Page Number Area

(c) The Editing Area

(d) The Text box Area

(e) The Rectangle Area

5. Which of the following page orientations are you able to set a document to use?

(a) Landscape and Horizon

(b) Horizon and Portrait

(c) Portrait and Vertical

(d) Landscape and Portrait

(e) Horizon and Vertical

6. The term given to the words entered on a spreadsheet, which usually name a column:

(a) Value

(b) Cell

(c) Label

(d) Graph

(e) Cell Address

7. In a spreadsheet, a function is

(a) a built in computation which summarizes values in specified cells

(b) a term for a number in a spreadsheet

(c) an intersection of a row and column

(d) a vertical division in a spreadsheet

(e) a horizontal division in a spreadsheet

8. Which of the following CANNOT be used to access a webpage using a browser?

(a) Type the URL into the address bar

(b) Type an address into the status bar

(c) Click on a link found in Favorites or Bookmarks

(d) Click on a link found in History

(e) Click on a link on another webpage

9. Which of the following is an email application?

(a) Microsoft Outlook

(b) Windows

(c) Unix

(d) Microsoft Word

(e) Microsoft Excel

10. Which of the following is NOT an option when sending an email

(a) To

(b) From

(c) Cc

(d) Bcc

(e) C

Exercises

Open-Ended Questions

1. Differentiate between general purpose and special purpose Applications Software.

2. List and briefly explain the main features of word-processing software packages.

3. What are the benefits of using presentation graphics software during a talk or presentation?

4. For what reasons users may wish to add narration to their slide show?

5. Name a few types of graphs which may be generated by a spreadsheet.

6. One important feature of a spreadsheet is the use of formulae. What are they?

7. Discuss the components of a DBMS.

8. What is the purpose of a browser?

9. One feature of email software is the address book. What is an address book and what is its use?

10. What is an email signature in an email message?

Chapter 8

Systems Development

Learning Objectives

Upon completion of this unit, you should be able to do the following:

1. Define a system

2. Identify the motivation for Systems Analysis and Design

3. Understand the importance of the different phases in the System Development Life Cycle

4. Describe the techniques available for gathering information

5. List the tools and techniques used in analysis

6. Understand the steps required for a good system design

7. Identify the different tasks required for system development

8. Understand the importance of maintenance after the system is up and running

OVERVIEW

The chapter will give an overview of Systems Analysis and Design. Learners will understand that Systems

Analysis and Design is a problem-solving procedure for examining and improving an information system.

Moreover they will investigate the need of an organisation for a new system. The chapter will give an overview

of the different phases in the System Development Life Cycle and learners will understand the importance of

each of them. An appropriate case study will be used throughout the chapter to help learners understand each

of the concepts explained.

8.0 Introduction

The need of an organisation for a new computerised system often leads to the process of Systems

Development. This is a problem-solving procedure for examining and improving an information system. This

chapter will investigate each of the different phases making up the System Development Life Cycle.

8.0.1 What is a system?

One of the most general and powerful notions of order and structure is that of a system. A system may be

defined as an interrelated set of components that are viewed as a whole. The components work together to

perform a function or to achieve an objective. A boundary separates a system from its environment. The

boundary defines the limits of the system. Inside the boundary is the system to be studied, described,

structured and usually, changed. Outside the boundary is the environment or context, the part of the world to

be ignored except for a few important interactions at the boundary between the system and its environment.

Figure 8-1 System Boundary and Environment

Thus, a system has:

Components – the basic parts or elements that make up the system

A structure – the way in which the components are organized

Function – the task, activity, or work that the system performs

Objective – the human goal or purpose that the system serves in carrying out its function.

Many systems perform multiple functions and serve several objectives. Examples of a system include an

educational system, a computer system, the solar system, an economic system, the human body.

A computer system for instance has:

Components: a CPU, a monitor, a keyboard, a mouse, a power supply, speaker Structure: how the different components are connected to each other

Function: provides the user with the ability to work with functions and formulas in spreadsheets

Objective: assists in the generation of financial reports of a company

An information system (IS) is an arrangement of people, data, processes, communications, and information

technology that interact to

accomplish specific information-handling operations, such as communication, computation,

dissemination, processing, and storage of information, which is essential to running an organization

support and improve day-to-day operations in a business

support the problem-solving and decision-making needs of management and users.

8.0.2 Motivation for Systems Analysis and Design Systems Analysis and Design is a problem-solving procedure used by companies to develop and maintain

information systems that perform basic business functions. The main goal of this process is to improve

employee efficiency by applying software solutions to key business tasks.

A number of issues have to be addressed before embarking on the process of Systems Analysis and Design.

These are:

Problems - undesirable situations that prevent the organization from fully achieving its purpose,

goals, and/or objectives, and that require corrective action. Some examples are:

- Goals are no longer being met

- Work completed slowly

- Work done incorrectly

- Changes in employee behaviour

Opportunities - chances to improve the organization even in the absence of specific

problems/complaints.

Directives - new requirements that are imposed by management, government, or some external

influence. Examples of these include:

- Organizational growth

- Mergers and acquisitions

- New marketing opportunities

- Revisions in governmental regulations

- Availability of new technology

8.1 The Systems Development Life Cycle

A structured approach must be used in order to ensure success in the process of system development. A

Systems Development Life Cycle (SDLC) is a very formal and precise system development process that

defines a set of activities, methods, best practices, deliverables, and automated tools that system developers

and project managers are to use to develop and maintain information systems and software. The SDLC

consists of a series of steps used to manage the phases of development for an information system. The four

main phases are:

Analysis

Design

Implementation and Testing

Maintenance

At any stage, however, we might discover previously unidentified problems and a return to previous stages

may thus prove necessary.

The following figure shows the different phases of the SDLC.

Figure 8-2 Phases of the SDLC

The purpose of viewing system development in this way is to set up a general framework within which system

development can proceed. This technique helps to achieve greater control on the computerization project.

Thus, the amount of time to be allocated to each phase can be agreed upon. Furthermore, the completion of

each phase is a milestone which consists of monitoring the project progress by:

Ensuring that the time frames specified for each phase is being respected as far as possible Checking that the tasks and activities enumerated for that phase have been completed

Checking that the deliverables/progress reports have been submitted to the appropriate persons

Making a decision about whether we proceed to the next phase

Systems Analysis is the study of the current system functions in order to identify the problems encountered

or needs. As a result, new requirements are specified and alternatives for system improvement are considered.

The new requirements guide the System Design process which consists of modeling the new system and

specifying the hardware and software considerations. During System Implementation, new hardware and

software are acquired, developed and tested. The new information system is installed and people are trained to

use it. System Maintenance is an ongoing phase, whereby the system is periodically evaluated and updated

as needed.

8.3 Systems design The next stage of the SDLC is Systems Design. Systems design is defined as those tasks that focus on the

specification of a detailed computer-based solution. Thus, whereas systems analysis placed emphasis on the

business problem, systems design places emphasis on the technical or implementation concerns of the system.

The process of design begins with a statement of the objectives of the desired system. These are made as

explicitly as possible so that the system devised by the designers can be tested to determine whether it meets

the objectives of the people who will use it. When the system can be shown to satisfy its objectives, the design

process may terminate.

During Systems Design, the analyst focuses on three basic elements:

The output that must be provided by the system The source data, or input that the user will provide to the system

The processing needed to produce the output, given the input

The different activities in comprise the Design phase are:

1. Design the overall system structure

Designing the system structure means defining its components (the program units or modules), the

relationships between them (the connections by which control is passed from one module to another at

execution time), and the information flows between pairs of modules.

2. Designing the details

This involves the design of the different programs to run on the system as well as the design of all system

inputs and outputs, which include the layouts of all the source documents and reports as well as other kinds of

information displays. The user interfaces with the automated system are also designed at this stage. This may

include manual procedures for collecting and distributing system outputs. For interactive systems, user

interface design includes the detailed procedures for entering data, requesting output, and initiating other

system functions.

3. Design the data stores or database

This entails defining physical storage structures for the logical data structures described in analysis. For

example, it may be decided to store details of customers in a table with fields customer name, address, phone

number, amount owed. The decision about where to store all this information about customers will depend on

the hard disk space required, among other considerations.

4. Design the system according to the existing hardware and software environment

The design is then adjusted to the hardware and system software environment in which it will be executing,

i.e. it is important to keep in mind the existing infrastructure already existing in the organisation.

5. Package the design specification

In this step, the portions of the design model are collected in final form into a document that will guide the

development of the system.

8.4 Implementation and Testing After the new system has been designed, it is now ready to be implemented. Computer programs are written

and tested individually, then merged together to form the entire computerised system which will then be ready

to be installed and used in the organisation.

Systems Implementation consists of three tasks:

System Development

Testing

Installation

8.4.1 System Development During this phase, computer hardware is purchased and the software is developed. That means that we

actually start coding the program. If design is performed in a detailed manner, writing of programs can be

accomplished without much complication. Programming tools like Compilers, Interpreters, Debuggers are used

to generate the code. Different high level programming languages like C, C++, Pascal, Java are used for

coding as discussed in Chapter

5. With respect to the type of application, the right programming language is chosen. The major activities carried out during this phase are:

Acquire the hardware (Personal Computers and other peripherals, including printers, scanners,

speakers, floppy disks, and so on)

Build the database, if the system requires one

Develop the software (coding and testing)

8.4.2 System Testing Once the code is generated, the program testing begins. Testing is important in order to verify that the system

is performing the required tasks correctly and effectively. Different testing methodologies are available to

detect the bugs that were left out during the previous phases. Sample data is fed into the system. The

processed information is then evaluated to see whether results are correct, i.e. whether the output corresponds

to what was expected. This may take several months if the system is complex. Some of the testing is

completed by programmers alone, some of it by system analysts in conjunction with programmers. Another

type of testing is acceptance testing, carried out by users of the system.

8.4.3 Installation Any hardware that has been purchased will be delivered and installed. Software, which was designed in the

Design phase, and programmed in the Development phase of the SDLC, will be installed on the PCs that

require it. Any person that will be using the program will also be trained during this phase of the SDLC.

During this phase, both the hardware and the software are tested again in the new environment. Although the

programmer will find and fix many problems, almost invariably, the user will uncover problems that the

developer has not been able to detect.

Since implementing the new system into the organisation involves a transition from an old system to a new

one, users should anticipate some difficulties during system start-up as they learn their new tasks and

procedures. The more these difficulties are minimised through well-designed system interfaces, proper user

training, and cooperation among all the participants, the better the transition will be.

8.5 Maintenance Software is very often prone to changes once it is delivered to the customer, mostly due to changes in business

policies, or client requirements. The process of changing a system after it has been delivered and is in use is

called software maintenance. Maintenance has two parts: a systems audit and a periodic evaluation.

In the systems audit, the system’s performance is compared to the original design specifications. This is to

determine if the new procedures are actually furthering productivity. If they are not, some further re-design

may be necessary.

After the systems audit, the new information system is periodically evaluated and further modified, if

necessary. All systems should be evaluated from time to time to see if they are meeting the goals and

providing the service they are supposed to.

The changes brought to the system after this phase may involve

simple changes to correct coding errors,

more extensive changes to correct design errors or

significant enhancements to correct specification errors or accommodate new requirements.

There are three types of maintenance:

Perfective maintenance: Changing a system to make it meet its requirements more effectively

Adaptive maintenance: Changing a system to meet new requirements

Corrective maintenance: Changing a system to correct deficiencies in the way it meets its

requirements

A post implementation review is also carried out so as to evaluate system performance and project

performance.In evaluating system performance, the following issues are addressed:

Have the operational expectations for the system been met?

Have the predicted benefits been achieved?

In judging project performance, the following issues are addressed:

Were the stated project goals and objectives achieved?

What is the relationship between estimated and actual development costs and schedules? What are

the explanations for any variances?

When evaluating the merit of a system, the evaluation criteria that are usually taken into consideration are:

Goals are concerned with whether the new system meets its intended objectives.

Time criteria encompass various timing aspects associated with the system, such as elapsed time,

transaction time, overall processing time, etc.

Cost criteria encompass various costs aspects associated with the system, such as the annual cost of

the system, per unit cost, maintenance cost, etc.

Reliability is concerned with whether the system suffers from fewer or more breakdowns or crashes

than was previously the case.

Capacity is concerned with whether the system is able to handle average or peak workloads.

Efficiency is concerned with the amount of resources used by the system compared to what was

previously the case.

Productivity is concerned with whether productivity has increased through use of the new system.

Accuracy is concerned with whether the new system produces fewer processing errors than the

previous one.

As we have seen in the chapter, incorporating a new system in an organisation or converting from an old

system to a new one is not a straightforward process. All stages of the System Development Life Cycle have to

be undergone in order to ensure proper analysis, design and implementation of the system. If all guidelines are

correctly followed, the need to go back to previous stages will not arise. Therefore, what is of utmost

importance in such a process is proper project management in order to ensure a good allocation of resources,

in terms of time, budget and human resources to each of the stages of the SDLC.

8.6 Further readings

Hawryszkiewycz, I.T. , Introduction to systems analysis and design, Prentice-Hall

Perry Edwards, Systems Analysis and Design, McGraw-Hill 1993

Exercises

Multiple Choice Questions

1. An arrangement of people, data, processes, communications, and information technology is

(a) A system

(b) An information system

(c) A boundary

(d) An environment

(e) A structure

2. The task or activity that a system performs is its

(a) Component

(b) Structure

(c) Function

(d) Objective

(e) Operation

3. Which one of the following is not a task carried out in preliminary investigation?

(a) Identify problems of the current system

(b) Identify functions to be performed

(c) Identify the data which needs to be stored

(d) Identify objectives of the new system

(e) Identify constraints placed on the project

4. Information Gathering is an activity of:

(a) Preliminary Investigation

(b) Design

(c) Data Analysis

(d) Detailed Investigation

(e) Implementation

5. Which Information Gathering technique is a good way of confirming information gathered through other

techniques?

(a) Interviews

(b) Questionnaires

(c) Performance Indicators

(d) Observation

(e) Study of Existing Documents

6. A useful tool during analysis is the

(a) Data flow

(b) Database

(c) Data store

(d) Data capture

(e) Data flow diagram

7. Which phase of the SDLC focuses mostly on input, output and processing?

(a) Analysis

(b) Design

(c) Implementation

(d) Testing

(e) Maintenance

8. Which of these tasks is not performed in System Development?

(a) Purchasing of personal computers

(b) Writing code

(c) Building the database

(d) Training of users

(e) Testing the software

9. Bugs in the system are discovered during:

(a) Testing

(b) Training

(c) Systems Audit

(d) Post Implementation Review

(e) Installation

10. If the implementation of the new system has brought about a reduction in the amount of resources used,

then, the new system is said to be more

(a) Productive

(b) Efficient

(c) Costly

(d) Reliable

(e) Accurate

Exercises

Structured Questions

1. In terms of components, structure, function and objective, define the following systems:

(a) An educational system

(b) The human body

(c) A football game

2. Give an example of each of the following which would lead to the systems analysis and design of a company

involved in the production of shoes:

(a) Problem

(b) Opportunity

(c) Directive

3. What is the System Development Life Cycle (SDLC)? List the main phases of the SDLC.

4. At the end of Preliminary Investigation, the system analyst writes a report to management. After discussing

over this report, management will decide either to proceed with or give up the project. Briefly describe the

contents of this report.

5. List the techniques of information gathering. For each of the following, identify which technique should be

used:

(a) To examine recorded operating procedures

(b) To collect quantitative information

(c) To collect qualitative information

(d) To solidify hazy understanding regarding the system

6. What is the purpose of a Data Flow Diagram? Briefly describe each of the components making up a DFD.

7. Describe the main tasks performed in Systems Design.

8. In software development, programming tools are used to generate code and high level programming

languages are used for coding. Give some examples of each.

9. Differentiate between Systems Audit and Post Implementation Review.

10. List and explain the 3 different types of maintenance?

Chapter 9

Computer Networks

Learning Objectives

Upon completion of this unit, you should be able to do the following:

1. Understand what computer networks are.

2. Understand the reasons why organisations set up computer networks.

3. Explain what is a LAN, MAN and WAN.

4. Differentiate between an Operating System (OS) and a Network Operating System (NOS).

5. Identify the common types of servers used in LANs.

6. Understand what peer to peer and server based networks are.

7. Identify some of the hardware associated with computer networks

8. Evaluate and select the type of cable appropriate for a LAN

9. Understand the different types of topologies used in LANs

10. Define the basic wireless communication concepts and terminologies.

11. Explain the components and functions of wireless networks.

12. Recognize the capabilities and applications of wireless LANs.

13. Discuss how wireless communications can be used to benefit businesses.

OVERVIEW In this chapter, the learner will be introduced to some basic concepts of networks. The reasons why networks are set up and the benefits derived from them have also been exposed. The learner

will understand that the basic computer networks commonly include microcomputers (PCs), servers and shared resources (such as network laser printers). Also, cables (medium) used to connect devices on a network, as well as network architectures and topologies have been thoroughly discussed. To make things clearer, these notions have been seconded by simple diagrams showing their practical use or application. This chapter also introduces students to wireless networking. The advantages of wireless networks

over traditional wired networks are discussed. An overview of the different types of wireless networks and standards is given. Moreover, the use of mobile and wireless computing to provide the infrastructure for mobile commerce (conducting e-commerce wirelessly, any time and from any place) is discussed.

9.0 What is Network? A network involves connecting computers together using a medium for the purpose of sharing information and resources.

For example, a network can connect two or more computers to share resources such as files, a printer, an Internet connection, applications, or a combination of these in an organisation.

Eventually, with a network, computers can receive emails from each other, send files to each

other, send instant messages to each other and perform a variety of other things, as discussed later in this chapter.

9.1 Primary reasons for setting up a network

Below is a list of reasons for setting up a network. 1. Sharing of data. For example: documents, files, programs (or software) as well as applications may be stored on the drive of a server (usually on a shared folder/director) and made available to users who have a connection on the network to that server. Electronic mail (email), the World Wide Web and distributed databases are common means of sharing information.

2. Sharing of hardware. For example, several computers might be networked together in a wired (or wireless) network to share a common printer. Modems, fax machines and CD drives can be

shared in a similar way. 3. Reliability. With a network, we can have alternative sources of supply, like replication of data on different machines. The most crucial thing for a company is its data - a machine can be

replaced but data cannot. If a company like a bank loses its transactions for a single day or even those of an hour, then it will lose its credentials. 4. Lower costs. The prices of personal computers are affordable nowadays. Hence system designers have built networks consisting of personal computers, one per user, with data kept on one or more shared file server and with one (or more) printers accessible to all the users.

5. Better information flow. Networks have enabled the development of mailing list whereby a single mail can be sent to a group of individuals simultaneously. 6. New Services. Email, video conferencing, E-commerce, newsgroups, chat are now available due to networks.

9.2 Common network terms The following is a list of terms which you will come across in this chapter:

Node: A node is any device that is connected to a network. E.g: a computer, printer.

Server: A server is a computer that shares resources with other nodes and clients.

Servers are usually computers with powerful processing capabilities, high disk storage and

high memory capacity.

Client: A computer that requests and uses shared resources available usually from a

server (or from other nodes).

Shared Data: Files, programs which are provided by servers (placed in shared

folders/directories) and which are available to computers (clients) on the network.

Protocol: Defines a common set of rules that specify how computers on a network

communicate. Ethernet and Token Ring are examples of network cabling protocols, whilst

TCP/IP is the predominant network communications protocol.

Topology: Defines the geometric arrangement of a computer system. Common topologies

include bus, star and ring arrangement.

Architecture: Networks can be broadly classified as using either a peer-to-peer or client-

server architecture.

Network Interface Card (NIC). A card placed in the expansion slot of a computer that

enables it to communicate with a network.

Medium. A cable (with one or more wires), a glass fiber conducting light, a wireless

transceiver or any other medium over which data can be sent from one node to another.

Networks can be very simple, such as a small group of computers that share information –

like computers in a university lab which is connected to a server, where lecturers place

assignments and tutorials for their students or they can be very complex, spanning large

geographical areas – like the Internet. Because each network is different and probably

utilises many diverse technologies, it is important to understand the three major types in

which networks can be categorized – Local Area Network (LAN), Metropolitan Area

Network (MAN) and Wide Area Network (WAN).

9.3 Local Area Network (LAN) A network with computers and peripheral devices in close proximity (the same building or spread over a small geographical region) is known as a LAN. The area serviced by a LAN may be some physical area, like the floor of a building, a networked office building or a laboratory. Sometimes one building will contain a few small LANs, and occasionally a LAN will span over a group of nearby buildings or it may be logically grouped according to the function that the computers need to serve. It is common for a large site to have several LANs in the same building, each serving a slightly different purpose.

Today’s technology allows a larger LAN, but practical administration limitations require dividing it

into small, logical areas called workgroups. A workgroup is a collection of individuals (a sales

department, a finance department or a library) who share the same files and databases over the

LAN.

Characteristics of a LAN

They provide high-speed communication.

Communication channels between computers in a LAN are usually privately owned. That is,

all equipment, cabling and devices belong to the enterprise in which the LAN has been set

up.

LANs are simple and inexpensive. Standard computers, like PCs, can be used as network

servers and workstations. This provides a great deal of design flexibility, relatively easy

maintenance and helps keep costs to a minimum.

Channels in a LAN are of relatively high capacity (10 Mbps to 100 Mbps)

They support many types of protocols.

Channels in a LAN are relatively error-free (a bit rate error of 1 in 109 bits transmitted).

9.3.1 Network Operating System (NOS) Network Operating Systems (NOS) are typically used to run computers that act as servers in a

network. They provide the capabilities required for network operation. NOS uses networking protocols to share system resources among other users connected to the network. NOS has in-built security features such as access security. More advanced NOS support file access security.

Functions provided by a NOS.

Account administration for users

File sharing

Print sharing

Backing up data

Security

Example of Network Operating System

Windows 2000 Server – It can use multiple processors and run on Intel or RISC

computers.

9.4 Metropolitan Area Network (MAN) A Metropolitan Area Network connects an area larger than a LAN but smaller than a WAN that usually spans a city or a campus. They typically use optical fibre connections or wireless infrastructure to link different sites. For instance, a university or college may have a MAN that joins together many of their local area

networks (LANs). Then from their MAN they could have several links to Wide Area Networks (WANs) to other universities or the Internet.

Figure 9.2 Example of a MAN

Characteristics of a MAN

MANs connect networks that are non-contiguous.

MANs are usually located within a local calling area.

The network size of a MAN falls intermediate between that of a LAN and a WAN. A MAN typically covers an area of between 5 and 50 km diameter.

A MAN (like a WAN) is not generally owned by a single organisation. The MAN, its

communications links and equipment are generally owned by either a consortium of users or by a single network provider who sells the service to the users.

The level of service provided to each user in a MAN must be negotiated with the MAN operator, and some performance guarantees are normally specified.

A MAN often acts as a high speed network to allow sharing of regional resources (similar to a large LAN).

A MAN is also frequently used to provide a shared connection to other networks using a link to a WAN.

Telecommunications facilities to link the locations together are usually provided by local

telephone companies or Alternate Service Providers (ASPs).

9.5 Wide Area Network (WAN) As the term implies, a WAN spans a large physical distance. A WAN like the Internet spans most of the world!

A WAN is a geographically dispersed collection of LANs. A network device called a router connects

LANs to a WAN.

WANs differ from LANs in several important ways. Like the Internet, most WANs are not owned by

any one organisation but rather exist under collective or distributed ownership and management.

WANs use technology like ATM, Frame Relay and X.25 for connectivity. Most networking

professionals define a WAN as any network that uses routers and public network links.

Figure 9-3 Example of a WAN

Characteristics of a WAN

In a WAN, multiple users are interconnected.

Computers are spread over a wide geographical area.

WANs support data transmission across public carriers, i.e., the communication channels

between the different LANs/machines in the WAN are usually provided by a third party. For

example: a telephone company or a public data network proving dial-up lines, dedicated

lines, packet switching, satellite carrier etc.

Channels in a WAN are of relatively low capacity (128/256/512 Kbps). However, with the

emergence of new technologies, high capacity WAN channels are today available.

Channels in a WAN are relatively error-prone (a bit error rate of 1 in 100,000 bits

transmitted).

9.5.1 Difference between WANs and LANs WANs differ from LANs in the following ways:

WANs cover greater distances.

WAN speeds are slower.

WANs can be connected on demand or permanently connected - LANs have permanent

connections between stations.

WANs can use public or private network transports; LANs primarily use private network

transports.

9.6 Network Architectures A network architecture is a design of a computer network in which each computer or process on the network is either a client or a server. There are two types of network architectures: peer-to-

peer and client/server (server-based) networks.

9.6.1 Peer-to-Peer Networking

It is a type of network in which each workstation has equivalent capabilities and responsibilities. This differs from client/server architectures, in which some computers are dedicated to serving the

others. In a peer-to-peer network, there are no dedicated servers. All computers are equal and therefore referred to as peers. Peer-to-peer networks are also called workgroups.

Figure 9-4 Two possible configurations of peer-to-peer network

Key Characteristics:

Peer-to-peer networks are simple, not expensive and easy to implement. Users manage their own data.

Degradation of workstation performance is observed as more users are connected to the

network.

The overall system is easy to use and well integrated.

Users are responsible for managing their own data. They act as their own administrators.

Hence, low level of security is required.

A peer-to-peer network would be appropriate when:

10 or fewer users in the same physical area Users share resources, such as files and printers, but no specialized servers exist.

Security is not an issue.

Organisation and network will experience limited growth in near future.

9.6.2 Client/Server network (server-based network)

Figure 9-5 Two possible configurations of a client/server network

Client/server is a computational architecture that involves client processes (machines) requesting service from server processes (servers). In general, client/server maintains a distinction between processes and network devices. Usually a client computer and a server computer are two separate devices, each customised for their designed purpose.

For example, a Web Server will often contain large amounts of memory and disk space, whereas

Web Clients often include features to support the graphic user interface of the browser such as

high-end video cards and large-screen displays.

Key Characteristics:

In an environment with more than 10 computers, a peer-to-peer network would not be appropriate. In such instances, server-based network come into play.

Server-based networks are nowadays becoming the standard.

Server-based networks are used when the need for centralisation of data and other

resources are felt.

The centralisation makes the management and control of data and resources easier.

Access to data and resources in a server-based network are controlled – requiring a highly

effective security system.

The software running on the server is a Network Operating System, to provide for the

proper network environment for the server and clients accessing it.

9.7 Types of servers commonly used in networks File Server: A file server holds and distributes files. It is a form of disk storage that hosts files

within a network. File servers do not need to be high-end but must have enough disk space to incoporate a large amount of data. Many people mistake file servers for a high-end storage system, but in reality, file servers do not need to possess great power or superfast computer specifications.

Print Server: A print server controls and manages one or more printers for the network. Proxy Server: A proxy server is a computer that offers a computer network service to allow clients to make indirect network connections to other network services. A client connects to the proxy server, then requests a connection, file, or other resource available on a different server. The proxy provides the resource either by connecting to the specified server or by serving it from

a cache. In some cases, the proxy may alter the client's request or the server's response for various purposes. Application Server: An application server is a server that hosts a network application. It is a

server computer in a computer network dedicated to running certain software applications. The term also refers to the software installed on such a computer to facilitate the serving (running) of

other applications. Web Server: A web server holds and delivers web pages and other web content using the Hypertext Transfer Protocol (HTTP). Mail Server: A mail server hosts and delivers e-mail. It is the electronic equivalent of a post office.

9.8 Network Hardware Networks are made up of both hardware and software. The

network hardware provides the physical connections between the network's various nodes and typically includes:

Network Interface Cards (NICs), one for each PC

Network cabling (sheathed copper wiring like telephone cords), which

connect each NIC to a central connecting device (like a hub or a switch).

Network devices such as repeaters, hubs, transceivers, bridges, routers and

switches, that are together responsible for connecting the various segments

of a network and for ensuring that information are sent to the intended

destination.

9.8.1 Network Interface Cards

Network Interface Cards (NICs) are used to connect a PC to a network. The NIC provides a physical connection between the networking medium and the computer's internal bus, and is

responsible for facilitating an access method to the network.

NICs contain connections for either coaxial or twisted pair cables (or both) (see figure below). If it

is designed for coaxial cable, the connection will be a BNC connection. If it is designed for twisted

pair, it will have a RJ-45 connection. Some Ethernet cards also contain an AUI connector. This can

be used to attach coaxial, twisted pair, or fibre optics cable to the card.

Figure 9-6 Network Interface Card

Most NICs are designed for a particular type of network, protocol, and media, although some can

serve multiple networks. Cards are available to support almost all networking standards, including

the latest Fast Ethernet environment. Fast Ethernet NICs will automatically set to the appropriate

speed.

A NIC is identified by a unique hardware address known as its Media Access Control (MAC)

address. The MAC address of the NIC is usually determined by commands provided by the

Operating System on which the computer is running.

9.8.2 Network cabling (network media or transmission media) Cable is the medium through which information usually moves from one network device to another. There are several types of cable which are commonly used with LANs. In some cases, a network will utilise only one type of cable, other networks will use a variety of cable types. The type of cable chosen for a network is related to the network's topology, protocol, and size.

Understanding the characteristics of different types of cable and how they relate to other aspects of a network is necessary for the development of a successful network.

Common of types of cables used in networks:

Twisted Pair (TP) Cable

Coaxial Cable

Fibre Optic Cable

9.8.2.1 Twisted Pair (UTP) cable Twisted pair cabling comes in two varieties: Shielded Twisted Pair (STP) and UnshieldedTwisted Pair (UTP). UTP is the most popular and is generally the best option for most networks installations.

Figure 9-7 UTP cable

The cable has four pairs of wires inside the jacket. Each pair is twisted with a different

number of twists per inch to help eliminate interference from adjacent pairs and other

electrical devices. The tighter the twisting, the higher the supported transmission rate and

the greater the cost per foot.

9.8.2.2 Coaxial Cable Coaxial cabling has a single copper conductor at its centre. A plastic layer provides insulation between the centre conductor and a braided metal shield. The metal shield helps to block any outside interference from fluorescent lights, motors, and other computers.

Figure 9-8 Coaxial cable

Although coaxial cabling is difficult to install, it is highly resistant to signal interference. In

addition, it can support greater cable lengths between network devices than twisted pair

cable.

9.8.2.3 Fiber Optic Cable

Fibre Optic Cable constitutes a technology that uses glass (or plastic) threads (fibres) to

transmit data. A fiber optic cable consists of a bundle of glass threads, each of which is

capable of transmitting messages modulated onto light waves. That is, light is transmitted

rather than electronic signals, eliminating the problem of electrical interference. This

makes it ideal for certain environments that contain a large amount of electrical

interference. It has also made it the standard for connecting networks between buildings,

due to its immunity to the effects of moisture and lighting.

Fibre optic cable has the ability to transmit signals over much longer distances than coaxial

and twisted pair. It also has the capability to carry information at greater speeds. This

capacity broadens communication possibilities to include services such as video

conferencing and interactive services. The cost of fibre optic cabling is comparable to

copper cabling; however, it is more difficult to install and modify. 10BaseF refers to the

specifications for fibre optic cable carrying Ethernet signals.

Figure 9-9 Fiber optic cable

9.9 Network Topologies

The term network topology refers to the layout or shape of a network. In other words, it tells us

how different nodes in a network are connected to each other and how they communicate with

each other. Networks must be arranged in a particular way in order to work properly. These

arrangements are based on the network hardware’s capabilities and the characteristics of the

various modes of data transfer.

The topology refers to the actual physical organization of the computers on the network.

Topologies vary depending on cost and functionality. There are five basic network topologies:

1. Bus

2. Ring

3. Mesh

4. Star

5. Tree

Each of these topologies has their advantages and disadvantages as we will discuss now.

9.9.1 Bus topology

A bus topology is a linear cable to which all network devices are directly attached. The main cable

is called the bus.

The principal advantages of the bus topology:

It can easily be expanded to include more nodes by just extending the two end points of

the main bus.

It is simple to install.

It is relatively inexpensive and uses less cable than other topologies.

The main disadvantages of the bus topology:

The entire network goes out of operation if there is a break in the main cable.

It is difficult to identify the problem when the network is down.

Figure 9-10 Bus topology

9.9.2 Ring topology A ring topology is an architecture that consists of a series of devices connected to one another by

unidirectional transmission links to form a single closed loop as shown in Figure 9-11. Each

device is connected directly to two other devices, one on either side of it. All messages travel

through a ring in the same direction either clockwise or counter-clockwise. A failure in any cable or

device breaks the loop and can bring down the entire network. Ring topologies are relatively

expensive and difficult to install, but they offer high bandwidth and the network can cover a longer

distance than bus topology.

Figure 9-11 Ring topology

The principal advantages of the ring topology:

The ring topology is relatively easy to troubleshoot. A station will know when a cable fault

has occurred because it will stop receiving data from its upstream neighbour.

It is expensive, because multiple cables are needed for each workstation.

It is difficult to reconfigure.

The principal disadvantage of the ring topology:

Not fault tolerant. A single cable fault can bring down the entire network.

9.9.3 Star topology Unlike those in a bus topology, each computer in a star topology is connected to a central point by a separate cable. The central point is a device known as a hub. Although this setup uses more cable than a bus, a star topology is much more fault tolerant than a bus topology. This means that

if a failure occurs along one of the cables connecting to the hub, only that portion of the network is affected, not the entire network. It also means that you can add new stations just by running a single new cable.

The principal advantages of the star topology:

Most network designers prefer the star topology, because these topologies make it simple to add network devices without disruptions to the network.

It is also easy to detect faults and to remove parts as each device has its own cable.

New stations can be added easily and quickly.

A single cable failure won't bring down the entire network.

The principal disadvantages of the star topology:

The star topology is susceptible to bottlenecking and single-point failure because all the

nodes rely on a single connection device (the hub).

Total installation cost can be higher because of the larger number of cables, but prices are constantly becoming more and more competitive.

Figure 9-12 Star topology

9.9.4 Tree topology

A tree topology is identical to the bus topology, except that branches with multiple nodes are

possible in this case. Also called a hierarchical or star of stars topology, tree topology is a

combination of bus and star topologies. Nodes are connected in groups of star-configured

workstations that branch out from a single root, as shown in Figure 9-13. The root node usually

controls the network and sometimes the network traffic flow. This topology is easy to extend.

When new users need to be added, it is simply a matter of adding a new central connection device.

Figure 9-13 Tree topology

The principal advantages of the tree topology:

This topology is easy to control. The root provides centralised management and monitoring.

The principal disadvantages of the tree topology:

If the backbone cable breaks, the entire segment goes down.

The tree topology is difficult to configure, wire, and maintain, especially in extensive

networks.

9.9.5 Mesh topology There are two main kinds of mesh topology: full-mesh and partial mesh.

In a full mesh topology, each node is physically connected to every other node. Full mesh is generally utilized as a backbone where there is a great need for fault tolerance, such as the backbone of a telecommunications company or Internet Service Provider (ISP). The primary advantage of this topology is that it is highly fault tolerant, when one node fails, traffic can easily be diverted to other nodes. It is also not especially vulnerable to bottlenecks. On the other hand, full mesh topology can require inordinate amounts of cabling if there are more than just a few nodes. A full mesh is also complex and difficult to set up.

In partial mesh topology, some nodes are organised in a full mesh scheme but others are only

connected to one or two in the network. Partial mesh topology uses fewer connections, and though

less expensive is also less fault-tolerant.

Figure 9-14 Partial Mesh topology

Figure 9-15 Full Mesh topology

The principal advantages of the mesh topology:

A mesh topology can become quite complex as wiring and connections increase

exponentially. The payoff for all this work is a more fail-safe, or fault-tolerant network

Computers or network devices can switch between these multiple, redundant connections

if the need arises

The principal disadvantage of the mesh topology:

Total installation costs can be very high because of the large number of cables and can

quickly become too complex.

A bad link may go unnoticed because network will still operate even if a cable goes wrong. In this section, we have looked at the physical organization of the network devices in the topologies. However, we have not looked at how data is transmitted among the network devices. This part is discussed in the following section and it refers to logical topology, indicating how data flow in the different physical topologies mentioned above.

9.10 Wireless Communication Wireless communication is fundamentally the art of communicating information without wires. The traditional computing environment that requires users to connect to a wired network to use its resources may be ineffective or inefficient in many situations. The solution is to make computers small enough that they are easy to carry or even to wear. Such mobile devices can communicate with traditional systems and infrastructure via wireline or, even better, wireless networks. The

ability to communicate and collaborate any time and from anywhere provides organisations with strategic advantage by increasing productivity, speed, and customer service. Therefore, wireless

communications represent a huge opportunity but also a challenge to today’s enterprises and individuals. Properly combined with traditional (wireline) voice and data solutions, wireless communications can provide productive and economical connectivity to anyone, anywhere, and anytime.

9.11 Wireless Networking A wireless network is a flexible data communications system, which uses wireless media such as radio frequency technology, to transmit and receive data over the air, minimizing the need for

wired connections. Wireless networks are used to augment rather than replace wired networks and

are most commonly used to provide last few stages of connectivity between a mobile user and a wired network.The widespread reliance on networking in business and the meteoric growth of the Internet and online services are strong testimonies to the benefits of shared data and shared resources. With wireless networks, users can access shared information without looking for a place to plug in, and network managers can set up or augment networks without installing or moving wires. Wireless networks offer the following productivity, convenience, and cost advantages over traditional wired networks:

Mobility: provide mobile users with access to real-time information so that they can roam

around in the network without getting disconnected from the network. This mobility supports productivity and service opportunities not possible with wired networks.

Installation speed and simplicity: installing a wireless system can be fast and easy and can

eliminate the need to fix cable through walls and ceilings.

Reach of the network: the network can be extended to places which cannot be wired.

More Flexibility: wireless networks offer more flexibility and adapt easily to changes in the

configuration of the network.

Reduced cost of ownership: while the initial investment required for wireless network

hardware can be higher than the cost of wired network hardware, overall installation

expenses and life-cycle costs can be significantly lower in dynamic environments.

Scalability: wireless systems can be configured in a variety of topologies to meet the needs

of specific applications and installations. Configurations can be easily changed and range

from peer-to-peer networks suitable for a small number of users to large infrastructure

networks that enable roaming over a broad area.

Figure 9-16 Wireless Internet Access

9.12 Types of Wireless Networks WLANS: Wireless Local Area Networks WLANS allow users in a local area, such as a university campus or library, to form a network or gain access to the network resources and the Internet. A temporary network can be formed by a small number of users without the need of an access point (discussed in next section), given that they do not need access to network resources.

WPANS: Wireless Personal Area Networks

The two current technologies for wireless personal area networks are Infra Red (IR) and Bluetooth

(IEEE 802.15), these are discussed in section 9.14. These will allow the connectivity of personal

devices within an area of about 30 feet. However, IR requires a direct line of site and the range is

less than other wireless technologies.

WMANS: Wireless Metropolitan Area Networks

This technology allows the connection of multiple networks in a metropolitan area such as different

buildings in a city, which can be an alternative or backup to laying copper or fibre cabling.

WWANS: Wireless Wide Area Networks

These types of networks can be maintained over large areas, such as cities or countries, via

multiple satellite systems or antenna sites under the administration of an Internet Service Provider

(ISP). These types of systems are referred to as 2G (2nd Generation) systems.

9.13 Wireless LAN A wireless local area network (LAN) is a flexible data communications system implemented as an

extension to, or as an alternative for, a wired LAN. Using radio frequency (RF) technology, wireless

LANs transmit and receive data over the air, minimizing the need for wired connections. Thus, wireless LANs combine data connectivity with user mobility. Wireless LANs have gained strong popularity in a number of vertical markets, including the health-care, retail, manufacturing,

warehousing, and academia. These industries have profited from the productivity gains of using hand-held terminals and notebook computers to transmit real-time information to centralised hosts for processing. Today wireless LANs are becoming more widely recognised as a general-purpose connectivity alternative for a broad range of business customers.

Figure 9-17 A Wireless LAN

Benefits of Wireless LANs

High-speed wireless LANs can provide the benefits of network connectivity without the restrictions

of being tied to a location by wires. There are many scenarios where this becomes interesting.

Wireless connections can extend or replace a wired infrastructure in situations where it is costly or

prohibitive to lay cables. Temporary installations represent one example of when a wireless

network might make sense or even is required. Some types of buildings or building codes may

prohibit the use of wiring, making wireless networking an important alternative.

A Wireless LAN can be built using an Access Point and laptop computers with wireless NICs. The Access points act as a central transmitter and receiver of WLAN radio signals. The devices in the WLAN should be equipped with a wireless Network Interface Card (NIC) in order to be able to communication with the Access Point. This enables the user to travel to various locations – meeting rooms, hallways, lobbies, cafeterias, classrooms, etc. – and still have access to their networked data. Without wireless access, the user would have to carry clumsy cabling and find a network point to plug into.

Figure 9-18 WLAN connected to a Wired Network

(a) Access Point (b)Wireless NIC (c) Laptop Wireless NIC

Figure 9-19 Wireless LAN Equipment

Beyond the corporate campus, access to the Internet and even corporate sites could be made

available through public wireless hot spots networks. Airports, restaurants, rail stations, and

common areas throughout cities can be provisioned to provide this service. When the traveling

worker reaches his or her destination, perhaps meeting a client at his/her corporate office, limited

access could be provided to the user through the local wireless network. The network can

recognize the user from another corporation and create a connection that is isolated from local

corporate network but provides Internet access to the visiting user.

In all these scenarios it is worth highlighting that today’s standards-based wireless LANs operate

at high speeds – the same speeds that were considered state-of-the-art for wired networks just a

few years ago. This bandwidth is certainly adequate to deliver a great user experience for a

number of applications or services via the PC or mobile device. In addition, ongoing advancements

with these wireless standards continue to increase bandwidth.

IEEE802.11 802.11 is the generic name of a family of standards for wireless networking. 802.11 standards,

developed by the Institute of Electrical and Electronics Engineers (IEEE), define rules for communication on Wireless Local Area Networks (WLANs). This standard is also known as Wi-Fi (wireless fidelity). Below is a brief discussion of the 802.11x standards, including the popular 802.11a, 802.11b and 802.11g.

802.11b: The first practical consumer wireless protocol widely manufactured was 802.11b. It is

limited to 11mbps (mega bits per second), much less performance you can get using a wired

Ethernet connection. The 802.11b standard operates on the 2.4GHz frequency (now a common

frequency for cordless phones).

802.11a: This was the next standard operating in the 5.8 GHz band. It provides 54mbps of

bandwidth (much faster than 802.11b) but it also has limitations. The 5.8GHz frequency has much

less penetration because it is more prone to obstacles (such as trees). But it also has its

advantages, there are much fewer devices using the 5.8GHz frequency making it an ideal standard

for administrators looking for as little interference (or noise from other wireless networks) as

possible.

802.11g: 802.11g is one of the latest wireless networking standard operating on the same

frequency as 802.11b but also providing the speed of 802.11a (54mbps). It is also fully backward

compatible with 802.11b wireless clients. This is the perfect standard to migrate to if someone is

considering a faster wireless network.

Bluetooth

Bluetooth is an alternative wireless network technology that followed a different development path

than the 802.11 family. Bluetooth supports a very short range (approximately 10 meters) and

relatively low bandwidth (1 Mbps). Bluetooth is a simple type of wireless networking that allows

the formation of a small network with up to eight devices being connected at once. Such devices

would include PDAs, Laptops, Mobile Phones and Personal Computers. However, Bluetooth may

also be found in keyboards, mice, headsets and mobile phone hands-free kits, amongst others.

Figure 9-20 Bluetooth Module

Its key features are robustness, low complexity, low power and low cost. The technology also

offers wireless access to LANs, Public Switched Telephone Networks (PSTN), the mobile phone

network and the Internet for a host of home appliances and portable handheld interfaces.

Bluetooth integration is further fueled by the demand for mobile and wireless access to LANs,

Internet over mobile and other existing networks, where the backbone is wired but the interface is

free to move. This not only makes the network easier to use but also extends its reach. The

advantages and rapid proliferation of LANs suggest that setting up personal area networks, that is,

connections among devices in the proximity of the user, will have many beneficial uses.

HomeRF

HomeRF, short for home radio frequency, was designed specifically for wireless networks in homes

- in contrast to 802.11, which was created for use in businesses. HomeRF networks are designed

to be more affordable to home users than other wireless technologies. The HomeRF allow for the

transmission of voice and data to a speed of up to 16 Mbps over distances of up to 150 feet - too

short a range for most business applications, but suitable for the home market that it was

specifically developed for. HomeRF is said to have better mechanisms in place to deal with

interference (from microwave ovens, for example) and to handle voice, video, and audio data

better than IEEE 802.11 standards. Nevertheless, IEEE802.11 is significantly faster than HomeRF -

albeit more expensive as well.

9.15 Mobile Computing and Commerce Mobile and wireless computing provide the infrastructure for mobile commerce - conducting e-commerce wirelessly, any time and from any place. They enable location-based e-commerce,

which is based on knowing where people are at any given time and on the ability to communicate

with them. While the impact of mobile computing on our lives will be very significant, a similar impact is already occurring in the way we conduct business. This impact is described as mobile commerce (also known as m-commerce and m-business), which is basically any e-commerce or e-

business done in a wireless environment, especially via the Internet. Like regular e-commerce applications, m-commerce can be done via the Internet, private communication lines, smart cards, or other infrastructures. M-commerce is not merely a variation on existing Internet services; it is a natural extension of e-business. Mobile devices create an opportunity to deliver new services to existing customers and to attract new ones.

Figure 9-21 Mobile Services

Mobile computing has two major characteristics that differentiate it from other forms of

computing: mobility and broad reach. These two characteristics, create five value-added attributes

that break the barriers of geography and time: ubiquity, convenience, instant connectivity,

personalisation, and localisation of products and services. A mobile terminal can fill the need for

real-time information and communication, independent of the user’s location (ubiquity). With an

Internet-enabled mobile device, it is easy and fast to access the Web, intranets, and other mobile

devices without booting up a PC or placing a call via a modem (convenience and instant

connectivity). Information can be customised and sent to individual consumers as an SMS

(customisation). And knowing where a user is physically at any particular moment is key to

offering relevant products and services (localisation). Vendors and telecommunication carriers can

differentiate themselves in the competitive marketplace by offering new, exciting, and useful

services based on these attributes. Such services will help vendors attract and keep customers and

increase revenues.

Figure 9-22 M-Commerce Service

An increasing number of online vendors allow customers to shop from wireless devices. For

example, customers who use Internet-ready cell phones can shop at certain sites such as

mobile.yahoo.com or amazon.com. Shopping from wireless devices enables customers to perform

quick searches, compare prices, order, and view the status of their order using their cell phones or

wireless PDAs. Wireless shoppers are supported by services similar to those available for wireline

shoppers. Moreover, a large number of applications exist that provide personal services to

consumers. As an example, consider the situation of a person going to an international airport.

Tasks such as finding the right check-in desk, checking for delayed flights, waiting for lost luggage,

and even finding a place to eat or the nearest restroom can be assisted by mobile devices.

9.15 Further readings

O’LEARY T.J. and O’LEARY L., Computing Essentials 1999-2000

UDAYAKUMAR P., Data Communication and Networks

GUPTA MANOJ KUMAR, Data Communication and Computer Networks

Exercises Multiple Choice Questions 1. In which of the following network cable is data (signals) transmitted as pulses of light?

(a) Unshielded Twisted Pair (b) Fibre Optic

(c) Coaxial (d) Network Interface Card (NIC) (e) None of the above

2. Which of the following network type is relatively error-prone?

(a) WAN

(b) LAN

(c) Star topology

(d) Client/server architecture

(e) Peer-to-peer architecture

3. A ___________ is a common set of rules that specify how computers on a network

communicate.

(a) Server

(b) Client

(c) Topology

(d) Protocol

(e) Medium

4. Which type of network server holds and distributes files in a network?

(a) Mail server

(b) Proxy server

(c) Web server

(d) File server

(e) Print server

5. In which of the following network topology does the entire network go out of operation if there

is a break in the main cable?

(a) Star topology

(b) Full mesh topology

(c) Bus topology

(d) Partial mesh topology

(e) Peer-to-peer network

6. UTP cable has four pairs of wires inside its jacket. Why is each pair twisted with a different

number of twists per inch?

(a) To help eliminate interference from adjacent pairs and other electrical devices

(b) To make each pair of wire stronger

(c) Because signals are carried quicker in twisted wires

(d) So that a pair can be easily distinguished from the other

(e) None of the above

7. Which one of the following mediums the wireless networks use to transmit data?

(a) copper wires

(b) optical fibre

(c) water

(d) air

(e) earth

8. Which type of wireless network would be more appropriate for a small university campus?

(a) Wireless Personal Area Network

(b) Wireless Metropolitan Area Network

(c) Wireless Local Area Network

(d) Wireless Metropolitan Area Networks

(e) Wireless Wide Area Networks

9. What is an Access Point?

(a) a wireless network interface card

(b) a central transmitter and receiver of WLAN radio signals

(c) a Bluetooth module

(d) a mobile entertainment system

(e) a wired connection

10. What is the approximate range supported by the Bluetooth technology?

(a) 10 meters

(b) 100 meters

(c) 1000 meters

(d) 10000 meters

(e) 100000 meters

Exercises Open-Ended Questions 1. Consider the setting up of network using a full mesh topology. Suppose that there are m stations (computers) and that on the average each link (connection) will use n metres of cable. Derive a formula in terms of m and n for: (a) The number of links (connections) and the cable length that will be required.

(b) The amount of cable length that will be required.

2. A laboratory has ten computers. The IT Manager is on the way of implementing a corporate

network using a bus topology. Coaxial cable will be used. Explain fully the risks such an option

might entail.

3. In a WAN, data may be transmitted along “public carriers”. Explain what you understand by

“public carriers” and provide one example of such a carrier.

4. What are the fundamental differences between a Local Area Network (LAN) and Wide Area

Network (WAN)?

5. Your advice has been sought for the selection of the transmission media (network cabling) to be

used to connect two LANs in two separate buildings. The available options are: coaxial, fiber optic

(10BaseF) or UTP cable. The distance between the two buildings is 1850 metres. Video, audio and

multimedia files will travel along the link, once it has been established. Justify, giving reasons, the

transmission media which would best suit the above connection.

6. What card should be inserted in the expansion slot of computer for it to gain access to a

network? What characteristic of such cards make them different from other similar cards?

7. Discuss the advantages of wireless networks over traditional wired networks.

8. Discuss the components and application of a Wireless LAN.

9. Differentiate between the Bluetooth and HomeRF wireless technologies. Give an example of the

application of each.

10. Discuss the advantages of mobile commerce. Give two examples of mobile commerce.