System software

• System software is the name given to the software that controls the hardware and how all other software works. The most commonly used system software, called an operating system, is Windows, made by the Microsoft Corporation. Without an operating system a computer just would not work.

Operating system

• Popular operating systems include Windows XP, Windows NT, Windows 2000, Mac OS X, LINUX and UNIX.

Booting• The process of starting a

computer is known as booting. The first thing a computer does when it is booted is to check that it is working properly. It does this by following certain instructions held on a ROM chip known as the BIOS.

• You can often see this happening as various lines of text briefly appear on the computer monitor. It will then look for an operating system (OS) to tell it what to do next. The operating system is loaded from disk to the computer’s random access memory (RAM).

Software ControlThe operating system controls how all

software applications, games or other programs work on the computer, such as:

• file management — saving, copying, renaming and deleting files

• multi-tasking — allowing more than one program to run (work) at the same time;

•for example, using a desktop publishing program while a graphics program is still running

• multi-user — allowing more than one user on a computer network to access the same file at the same time

• security — when passwords have been set, allowing only those with the correct password to use the computer.

Utility software• Utility software is specialized software

that tries to protect and maintain the system software, just like a mechanic maintains the smooth working of a car’s engine when it is serviced. Examples of the tasks undertaken by utility software include protecting software against damage caused by computer viruses, making copies of files (backing up) and recovering files after software has stopped working (crashed).

Hardware control• The operating system also sets the rules for

controlling hardware resources such as:

• peripherals — controlling peripheral devices such as keyboards, printers and scanners

• memory — controlling the amount of memory used

• CPU — controlling the time allocated to a task by the central processing unit (CPU)

• disk space — controlling the amount of disk space used.

QUESTIONS• 1 Explain what is meant by: a

booting b operating system.

• 2 Give four ways each in which an operating system controls hardware and software on a computer.

• 3 List three different operating systems used on computers.

Application software• Note: an operating system such as Windows is essential

for a computer to work.

• Most of the software we use regularly has been created to do specific tasks —for example, word processing or desktop publishing. The term for software such as this is application software or program.

• Application software is defined as programs that enable the computer to carry out one or more specific tasks.

General-purpose software• The most popular application programs

are those that are not specific to any organisation or business and can be used by anybody.

• The programs that you use at school or home — word processing, databases, spreadsheets, presentation, drawing and painting — will be such programs.

• These programs are known as general-purpose software, because the user decides what to use the software for. For example, you might want to use a word processor to write a letter or curriculum vitae (CV), or to design a poster for the school play.

• General—purpose software is much cheaper because it has been used by millions of people over a number of years and is generally error (bug) free. Popular examples of application programs (software) are given NEXT.

Custom-written software

• Custom-written software, which is also known as bespoke or tailor-made, can modify general-purpose software to perform specific tasks for the user.

• Again word processing, spreadsheet and database programs are examples of general purpose software that can be custom-made by automating certain parts of the software, or writing and adding programming modules to perform specific tasks.

Specialised software

• Specialised software is written solely for a specific task.

• Examples are software used by air traffic controllers to manage the flights of thousands of aircraft, accounting software, airline reservations software and computer-aided design.

• These are not general-purpose, since the users of these kinds of software (for example, accountants and engineers) are trained in a particular field of expertise.

• Since this software is specific to an organisation or business it can be very costly to create.

Integrated software • Many computers are sold with

integrated software already installed.

• Integrated software is the term for a program that includes all the major types of application (for example, word processing, spreadsheet and database) and brings them together into a into single software package.

• Microsoft Works is an example of integrated software. Some integrated software, such as AppleWorks, also includes presentation, drawing and painting features, making in effect six programs in one.

• The large software companies such as Microsoft, Corel and Lotus, sell their main application programs together in one package.

• Although packages such as these are sold as integrated software, it is not true integrated software, as all of the programs are still separate applications.

There are five advantages of integrated software

1. You get extremely good value for money, with up to six packages rolled into one.

2. You have to learn how to use only one package since the user interface is the same for choosing commands.

3.Data can be easily transferred from one integrated application to another, using cut, copy and paste.

4. It does not take up as much disk space as separate applications.

5. It takes up less memory than separate applications.

There are two disadvantages of integrated software

1.Not all of the features of single applications are included.

Therefore, the integrated software may not be up to the task you want it for.

2. Some integrated packages do not include all of the applications that may be required.

NOTE• Choosing software should be no different

from choosing any tool for a job.

• Just as in construction you decide whether to use a screwdriver or hammer to do a particular task, so with software you need to decide what it is you actually need to produce. and then choose the most appropriate program.

• This is very important when choosing programs to use for your coursework.

QUESTIONS 1 What is an application program? Give

three example of application programs.2 What is the difference between general

purpose and custom-written software?3 Give one advantage and one

disadvantage of integrated software.4 What application software would you use

for: a lots of calculations b searching and sorting datac creating an invitation?

User interfaces

• How you interact with a computer and use it is controlled by the computer—user interface.

• After the computer has booted up and loaded the operating system, you will see the user interface

• (also known as the human—computer interface).

There are three main types of user interface:

1.command-line interface

2.menu-driven interface

3. graphical user interface (GUI).

Command-line interfaces• Command-line interfaces require you to

type in commands using a special language

• This special language makes command line interfaces difficult to use, especially for new computer users.

• One example of a command—line interface is the Microsoft Disk Operating System (MS-DOS).

• In all cases, the command must be given at a specified prompt to indicate the drive on which the data is stored and the directory or folder in which the file is located. For example, a prompt which shows

• C:\> means that all commands will be performed with data on drive C:

• A command prompt with A:\> refers to a diskette in the disk drive. A sub-directory or folder is similar to a drawer in which related data items are held. Hence data may be stored in a folder such as C:\SBA> which is on the hard drive.

Some MS-DOS Commands

Menu-driven Interfaces• A menu is a list of options from which you

can choose what you want to do. Application programs use menus as an easy alternative to having to learn program commands.

• Menu-driven interfaces were developed to try to make the interface friendlier and easier to learn. You can control the computer by choosing commands and available options from a menu, using the keyboard or a mouse.

Graphical User Interfaces

• Graphical user interfaces (GUIs) are provided by the Windows and Macintosh operating systems.

• GUIs are presently regarded as the user interfaces which are easiest to use. As a result, all computers are now supplied with a GUI system installed,

• The best way to remember what makes up a GUI is to think of the word WIMP, which stands for Windows, Icons, Menus and Pointers.

WINDOWS• A window is that part of the screen

that holds its own document or message.

• Most computers now use window-based programs. A window can take up the whole screen or can be resized, moved or shrunk (minimised).

• Each time you open a folder, you see its contents in a new window More than one window can be open at the same time.

• This is particularly useful if you want to move from one window to another or to copy files from one window to another.

Icons • An icon is a tiny picture of an object

that is displayed on screen. Normally, you can use the icon in some way.

• For example, by using the mouse to double click on the icon of the Microsoft Excel spreadsheet program, you will start the program.

• Icons are designed to make things easier for computer users. Instead of having to remember commands, all you have to do is to remember what the icons look like.

• Icons are not just for programs. There are icons for folders, the recycle bin (wastebasket), disk drives and printers.

Menus• An advantage of using menus in Windows

or on a Macintosh is that, for most programs, the first few menus are always in the same order.

• They also carry out the same functions, no matter which program you are using.

• For example, the file menu is first and enables you, among other things, to create, save and print a document.

Pull-down means • Pull-down means (Fig 1.33) are activated

by clicking on the menu item (such as ‘File’) using the left mouse button.

• The menu pulls down just below the menu item, and you can scroll down through the various items. More complicated pull-down menus can produce additional pull-down or pop-up menus.

Pop-up menus • Pop-up menus are activated by

clicking anywhere on the document screen using the right mouse button.

• Some standard commands and options are available on these menus, including the cut, copy and paste commands.

Pointers• The most common pointing device is a

mouse. As the mouse is moved, a pointer moves around the screen.

• The pointer is a very important part of a GUI, as it enables you to control the computer and to choose window items, to select text in a document or cells in a spreadsheet, and to create drawings and shapes

• Other pointing devices include track pads, graphics tablets, joysticks and trackballs.

Improving interfaces • Software companies spend a great deal of

time and effort trying to improve the interface so that the computer is easy to use.

• An important part of this is to design the system software and application programs so that they work exactly the same way each time they are used, and the menus are always in the same place.

• People use computers for many hours a day. Therefore, the screen design and screen colours must be visually pleasing and soothing. Also, some colours might be impossible for the visually impaired to see.

QUESTIONS• 1 List three types of user interface.

• 2 Explain what is meant by a GUI and WIMP. Why do you think GUIs are the most popular user interface?

• 3 Give two important factors that should be taken into account when designing a user interface.

• 4 What is the difference between a pop-up and a pull down menu?

File Management Techniques

• Before you learn how to save your work and locate files and programs, you need to understand the rules of managing files and the folders they are stored in. This is called file management.

• Windows Explorer is a file management utility provided for organizing your files on storage devices such as diskettes, hard disk and CD.

• Windows maintains a directory for each disk, CD-ROM and drive, which provides a list of the filenames, type of files, date and time the files were created and the file size.

• Windows explorer can be opened in Microsoft Windows XP, for example, through the Start, Programs, Accessories menu.

Managing filesHere are some basic terms

you should know:

• File: Every document that you use is called a file. So, the program that is used to start an application, or the document you typed, are both called files.

Folder: Just as you would have a folder to keep notes or documents together, files are grouped together in folders (also called directories).The icon for a folder on the computer screen looks quite like a typical folder.

• Drive:Your computer may have many storage devices such as the hard drive, floppy drive, USB drive or CD drive. These devices contain the files and folders that you work with. Each drive is given a specific drive letter to distinguish it from the other drives.

• For example, the floppy drive is usually called drive A. If there is another floppy drive then it is called drive B. The hard drive is called drive C and so on. Network drives are usually further down the alphabet. like M or 0.

• Path: To locate a file, you may have to select the drive and then one or more folders, This sequence to get to the specific folder or file is called the path. Since you must first select the drive, a path always starts with a drive letter.

• Also, since it is a file or folder you are looking for, that file or folder name is the last in the path. for example, C:\CXC\Unitl.doc means that the file Uniti .doc is found in the CXC folder located

• on drive C. The backslash \ is used to separate the file, folder or drive name.

File names

• How do you choose a name for your file? A file name has two parts: FILENAME and EXTENSION. When you look at file names on the computer, they may look like filename.ext.

• In the past, file names had to have I to 8 characters in the FILENAME and 0 to 3 in the

• EXTENSION. Sometimes you may just see the filename since the extension may be hidden. Most programs have a default extension which they will assign to files that they save unless you specifically type in something different.

• You can create your own method for naming files based on the date, the type of document, the project it’s about, or whatever coding scheme you want. It may look confusing to others, but it is only important that you know what your file names mean. Just remember that what is obvious today may be obscure next week! Generally it is best to keep the filenames as simple and direct as possible.

• Extensions are associated with specific programs. For example, ‘cxc’ shows that the file is an executable, meaning that it starts a program or application. Here are some more examples:

• device.com — command file • autoexec.bat — batch file • uniti .doc — word processing file• intro.txt — text file (similar to word processing

file)• index.htm — hypertext document for the

Internet. • config.sys — system file

• A file name such as ‘Report to President for 2004.doc.’is called a long file name, meaning that it is longer than 8 characters plus 3 for the extension. It also contains spaces. These are legal and acceptable under Windows 93/98/XP and some other operating systems.

• Certain characters cannot be used in file names. They are reserved by the operating system for special uses.

• The characters: . , / \ : ; [ ] “|= are all illegal in a file name.

User back-up • Besides protecting the physical medium

you are using to store data, you must also consider what you can do to safeguard the data itself.

• If the disk is kept from physical harm, but the data gets erased, you still have a major problem. So what can you do to safeguard the data on which you rely?

Write protect

• This keeps your files from being overwritten with new data. For diskettes, you do this physically, by opening the write-protect slide so that you can see through the hole.

Make copies

• Make multiple copies on other diskettes. The more important the files are, the more copies in more secure places you need.

Data Processing• Data must be processed by the most

suitable means. It can then be transferred to one or more computer systems for more processing, for output or for storage.

• This processing can be achieved by three methods:

• batch processing

• on-line processing

• real—time processing

Batch processing

• A batch processing system is one where data is collected together in a batch before processing starts. With early computers data was entered on punched cards (or Hollerith cards), which were handled in batches, hence the term batch processing.

• Batch processing is most suitable for tasks where a large amount of data has to be processed on a regular basis. When a batch job begins, it will continue until it is completed, or until an error occurs.

• Examples of batch processing systems include those that process utility bills such as water and electricity, payroll systems and examination report card systems.

• Credit card companies also process billing in batches. The customer does not receive a bill for each separate credit card purchase but one monthly bill for all of that month’s purchases.

• The bill is created through batch processing, where all the data is collected and held until the bill is processed as a batch at the end of the billing cycle.

Advantages

• Once the data is submitted for processing, the computer may be left running without human interaction.

• The computer is only used for a certain period of time for the batch job.

• Jobs can be scheduled for a time when the computer is not busy.

Disadvantages

• There is always a delay before work is processed and returned since batch jobs are usually stored up over a period of time.

• It usually involves an expensive computer and a large number of trained staff.

On-line and real-time processing

• Computers and peripheral devices are on-line when they are connected to a main processor and turned on, so that the operator can interact with them.

• Examples of on—line processing include devices such are printers which are on—line when they are ready to receive data from the computer to print.

• Most printers have an on line button you can press to turn the machine on. If it is turned off then you are off-line. You can also be on-line if you are connected to, say, the Internet through a modem or network.

• A real—time processing system processes data without significant delay, making it always up-to-date. Since processing must be connected to one or more computers to process data, then it must also be on-line. However. note that on-line does not necessarily imply that processing is real-time since there may be some delay with an on-line system.

• Examples of real-time processing systems include anti-missile defense systems, airplane landing control system, flight simulation systems, electronic fund transfer systems and ticket reservation systems.

Advantages

• No significant delay for response.

• Information is always up-to-date.

• Output from the computer may be used to adjust and improve the input back to the system.

Disadvantages

• The computer must be dedicated solely to the task.

• The computer must be continually on-line.

Data Transfer

• Data transfer is the movement of information from one place to another. With computers this happens in three ways:

• within a single computer

• between a computer and other computers

• between a computer and external devices.

Within a computer

• The loading of the operating system when the computer is started is one example of data being transferred within a computer.

• The operating system data is transferred from hard disk to the computer’s memory (RAM).

• Data is also frequently transferred between software applications on a stand-alone computer.

• This can be done simply by copying and pasting or by the software itself opening or importing files that were created by a different software package.

• Importing is the term for transferring data from one program to another.

• For example, Microsoft Word will open web pages and documents created in other word-processing packages such as Word Perfect.

Between Computers

• Most computer users will, at some time or another, need to transfer files between computers. School students may need to transfer their work from a computer at home to the school network via a diskette or a Zip disk.

• Updates to software packages, such as Microsoft Office, can be downloaded from the Internet using file transfer protocol (FTP).

• Sometimes, however, transferring data between computers requires a little preparation as not everybody uses the same software. For example, one person might use Microsoft Access as a database, whereas another might use Lotus Approach.

• The solution to this is to convert the file into a common file format that can be read by all software packages without changing or damaging the data.

• This process is known as file conversion. In the example (next slide), converting the file to CSV (comma separated values) would enable it to be read by other spreadsheets or databases.

Saving an Excel spreadsheet in CSV format means that other spreadsheet or database programs can open the file

• Text, too, can easily be converted. Saving text in ASCII (American Standard Code for Information Interchange) format converts letters into binary code that can be read by any computer.

• There is a drawback, however, because saving a file as ASCII resuls in all formatting (bold, italic, etc.) being lost.

• To overcome this problem, files can be converted instead to Rich Text Format (RTE).

• RTF enables the file to be opened by other programs even those on computers running different operating systems as well as preserving all formatting.

• Another way of transferring data, made popular by the Internet, is by HTML (Hypertext Markup Language).

• Before transferring data, it is also sometimes necessary to reduce the file size. The process of reducing the size of a file for storage, or for sending via the Internet, is known as file compression.

• WinZip and Stuffit are popular programs for compressing files. File compression is important because some files, particularly picture, so video and animation files, can take up a large amount disk storage space.

• The larger the file size, the longer it takes to send via the Internet. This can mean that more money is spent on telephone calls.

• Users of the Internet will also know that web pages containing pictures can take a long time to load.

• Web designers try to get around this problem by reducing the file size of pictures -usually by saving them in JPEG (Joint Photographic Experts Group) format.

• When video is to be shown, this will be compressed using the MPEG (Moving Pictures Experts Group) format. Music will be compressed using MP3

QUESTIONS• 1 List three ways in which a computer

transfers information.

• 2 Explain what is meant by the terms file conversion and file compression.

• 3 Give one reason why many users need to convert files.

• 4 Give two reasons why you might want to use compressed files if you have a modem and access to the Internet.