BTEC HIGHER NATIONAL DIPLOMA

Assignment

Institute Name : IDM Computer Studies Pvt. Ltd.

Unit Name : Computer Platforms

Unit Value : Unit 1

Assignment Title : Old Students Association

Date given : 20th January 2010

Date to be submitted : 20th March 2010

Lecturer : Mr. J.Thava Nirojan

Rational

The objective of this assignment is to assure that the students have gained the relevant knowledge according

to the outcomes specified in the syllabus.

Assessment requirements to meet learning outcomes

1. Investigate computer systems

2. Investigate operating systems

3. Design a computer system

4. Test your computer system.

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ASSESSMENT CRITERIA

Criteria for PASS Possible evidence FeedbackY N Comment

P1.1.1 Select machine components or sub-systems appropriate to given tasks

Explain the Total Computer System(Task 1.1, 1.2)

P1.1.2 Evaluate the performance of the selected system

Select the appropriate computer system.(Task 1.3)

P1.2.1. Contrast the functions and features of different types of operating systems

Analyze the history & the evolution of the OS (Task 2)

P1.2.2 Understand how to customize operating systems

Identify the common features of Windows OS (Task 2)

P1.3.1 Investigate and identify the key components for a computer system for a particular user

Classify the primary components(Task 2, Task 3)

P1.3.2 Specify a complete computer system to suit a given task

Understanding the PC installation requirements and Realizing the function of the motherboard. (Task 2, Task 3)

P1.4.1 Produce a plan that checks the main hardware andsoftware components, using standard techniques

Prepare justification for upgrade / installation of new hardware(Task 3)

P1.4.2. Produce user documentation for your system

Produce a document describing the system requirements (Task 3)

P1.4.3 Produce a security policy for your system.

Not assessed in this assignment

P1.4.1 Demonstrate that the system meets health and safetyrequirements

Not assessed in this assignment

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Grade Descriptors for MERIT FeedbackY N Comment

M1 Identify and apply strategies to find appropriate solutions

Conduct research about the latest hardware and software resources which can be used in the computer system and include the specifications.

M2 Select / design appropriate methods / techniques

A range of techniques has been used to help inform technical and non-technical users of the operating systems (e.g. user manual)

M3 Present and communicate appropriate findings

Presentation and report provides a descriptions about the various new systems and peripherals.

Grade Descriptors for DISTINCTION FeedbackY N Comment

D1 Use critical reflection to evaluate own work and justify valid conclusions

Consider two three hardware and software configurations and perform a critical comparison.

D2 Take responsibility for managing and organizing activities

Substantial activities or investigations have been planned, managed and organized

D3 Demonstrate convergent / lateral / creative thinking

Student has shown extensive creative thinking in assembling the computers in order to improve the efficiency.

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Case Study

The Old Students Association of the school has asked the school management to get a technical and

financial feasibility report on the implementation of the new student computer center. They also promised to

undertake 50% of the total cost as their contribution to their old school. When you discussed this with the

teachers and the management of the school you documented the following requirements.

The computers should be in a position to run the latest GUI OS (Windows XP or later)

Office productivity tools like MS Office XP / Open Office, Image manipulation, Web Development

and Software Development tools, Anti Virus, Internet Browsers, System Utilities and Network

Troubleshooters. Wherever possible free and open source software are to be considered.

They want to use network enabled media for accessing and saving the student assignments and

tutorials.

They would like to use a USB based image scanner, optical media backup, multimedia keyboard and

a networked printer in the new setup.

You have written a comprehensive report covering the above items with features, comparisons, cost –

benefits and pros and cons, if any, of the suggested products. The school management is quite happy about

your report and has awarded your company the contract to build the computer center with the following

specifications.

1. Windows XP

2. Office productivity tools

3. GIMP or IrfanView

4. A free antivirus (such as AVG antivirus)

5. FireFox browser

6. Mozilla Thunderbird

7. Installation of Printers, optical media and scanner

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Task 1

Prepare a good report to identify the computer environment of school with completing following needs:

1.1 Explain the Total computer system (P1.1.1)

1.2 Identify and explain the functions of the parts of the entire computer system(P1.1.1)

1.3 Select the appropriate computer system with convince the customer requirements (Namely) (P1.1.2)

Outcomes and Assessment Criteria

Outcome Assessment Criteria

Investigate computer Systems Select machine components or sub-systems appropriate to given tasks (1.1, 1.2)

Evaluate the performance of the selected system (1.3)

Task 2 (P1.2.1, P1.2.2, P1.3.1, P1.3.2)

Research and prepare a word – processed document to describe the various new systems and peripherals

available in the market which could be used to implement the recommended solution.

1. New system boards

2. Processor and memory architecture.(Intel / AMD)

3. Disk drive systems (ATA / SATA)

4. Peripherals (USB / Firewire, Bluetooth and Wi – Fi Access)

5. Printers (Laser / DeskJet)

Outcomes and Assessment Criteria

Outcome Assessment Criteria

Investigate operating systems Contrast the functions and features of different types of operating systems (Task 2)

Understand how to customize operating systems(Task 2)Design a computer system Investigate and identify the key components for a computer

system for a particular user (Task 2) Specify a complete computer system to suit a given task (Task 2)

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Task 3 (P1.3.1, P1.3.2)

First explain the topologies and their advantages / disadvantages. Discuss the network topologies that suits

for this environment.

Outcomes and Assessment Criteria

Outcome Assessment Criteria

Design a computer system Investigate and identify the key components for a computer system for a particular user (Task 3)

Specify a complete computer system to suit a given task (Task 3)Test a computer system Produce a plan that checks the main hardware and software

components, using standard techniques (Task 3) Produce user documentation for your system (Task 3) Produce a security policy for your system. – Not assessed Demonstrate that the system meets health and safety

requirements - Not assessed

End of Assignment

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TASK 01

Computer system

A complete, working computer. Computer systems will include the computer along with any software and peripheral devices that are necessary to make the computer function. Every computer system, for example, requires an operating.

Components of a Computer System

Software is stored on hardware such as hard disks or tape. Monsters, Inc. can be recorded on a VCR tape. But the computer program (and the TV episode) is intangible. It is not the physical storage medium.

The hardware components of a computer system are the electronic and mechanical parts.The software components of a computer system are the intangible parts: the data and the computer programs.

The major hardware components of a computer system are:

Processor Main memory Secondary memory Input devices Output devices

You probably have a computer in front of you. The processor, main memory, and secondary memory devices are inside the systems unit. This is the metal box that is sometimes called "the computer." The monitor (the TV-like screen) is an output device.

Hardware Components

The terms "input" and "output" say if data flow into or out of the systems unit. The picture shows the major hardware components of a computer system. The arrows show the direction of data flow.

The bus is a group of wires on the main circuit board of the computer. It is a pathway for data flowing between components. Most devices are connected to the bus through a controller which coordinates the activities of the device and the bus.

The processor is an electronic device about a one inch square, covered in plastic. Inside the square is an even smaller square of silicon containing millions of tiny electrical parts. A processor may contain 100 million transistors. The processor is the "brain" of the computer system. It does the fundamental computing within the system, and directly or indirectly controls all the other components.

The processor is sometimes called the Central Processing Unit or CPU. A particular computer will have a particular type of processor, such as a Pentium or a SPARC chip. 

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Memory

The processor is the brain of the computer. All fundamental computing takes place in the processor. Other components contribute to the computation (by doing such things as moving data in and out of the processor), but the processor is where the fundamental action takes place.

Unlike a human brain, which combines memory with processing power, a computer processor has very little memory. It must rely on other components to hold data and programs and to save results. The memory in a computer system is of two fundamental types:

Main memory:o very closely connected to the processor.o the contents are quickly and easily changed.o holds the programs and data that the processor is actively working with.o interacts with the processor millions of times per second.

Secondary memory:o connected to main memory through the bus and a controller.o the contents are easily changed, but this is very slow compared to main memory.o used for long-term storage of programs and data.o The processor only occasionally interacts with secondary memory.

Main memory is where programs and data are kept when the processor is actively using them. When programs and data become active, they are copied from secondary memory into main memory where the processor can interact with them. A copy remains in secondary memory. Main memory is intimately connected to the processor, so moving instructions from the program and data into and out of the processor is very fast. Main memory is sometimes called RAM. RAM stands for Random Access Memory. "Random" means that the memory cells can be accessed in any order.

When people say that a computer has "128 megabytes of RAM" they are talking about how big its main memory is. One megabyte of memory is enough to hold approximately one million characters of a word processing document. (There will be more about bytes and megabytes later on in these notes.) Nothing permanent is kept in main memory. Sometimes data are placed in main memory for just a few seconds; only as long as they are needed.

Secondary Memory

Secondary memory is where programs and data are kept on a long-term basis. Common secondary storage devices are the hard disk and floppy disks.

The hard disk has enormous storage capacity compared to main memory. The hard disk is usually contained in the systems unit of a computer. The hard disk is used for long-term storage of programs and data. Data and programs on the hard disk are organized into files--named sections of the disk.

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A hard disk might have a storage capacity of 40 gigabytes. This is about 300 times the amount of storage in main memory (assuming 128 megabytes of main memory.) However, a hard disk is very slow compared to main memory. The reason for having two types of storage is this contrast:

Primary memory Secondary memory1. Fast2. Expensive3. Low capacity

4. Connects directly to the processor

1. Slow2. Cheap3. Large capacity

4. Not connected directly to the processor

Floppy disks are mostly used for transferring software between computer systems and for casual backup of software. They have low capacity, and are very, very slow compared to other storage devices.

Input and Output Devices

Input and output devices allow the computer system to interact with the outside world by moving data into and out of the system. An input device is used to bring data into the system. Some input devices are:

Keyboard Mouse Microphone Bar code reader Graphics tablet

An output device is used to send data out of the system. Some output devices are:

Monitor Printer Speaker

Input/output devices are usually called I/O devices. They are directly connected to an electronic module inside the systems unit called a device controller. For example, the speakers of a multimedia computer system are directly connected to a device controller called an audio card (such as a SoundBlaster), which in turn is connected to the rest of the system.

Sometimes secondary memory devices like the hard disk are called I/O devices (because they move data in and out of main memory.) What counts as an I/O device depends on context. To a user, an I/O device is something outside of the system box. To a programmer, everything outside of the processor and main memory looks like an I/O devices. To an engineer working on the design of a processor, everything outside of the processor is an I/O device.

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Software

A computer that is dedicated to running a program that controls another device is an embedded system. An embedded system is usually embedded inside the device it controls. Usually they run just one program that is permanently kept in a special kind of main memory called ROM (for Read Only Memory). More processor chips are sold per year for embedded systems than for all other purposes.

Software is the programs and data that a computer uses. Software is kept on some hardware device such as a hard disk or floppy disk, but it itself is intangible. Say that you have a floppy disk with a program saved on it. Now say that you erase the program from the disk. The atoms and molecules of the disk are the same ones as before, but now the program is "gone." The intangible software has been removed without removing anything tangible.

Software consists of both programs and data. Programs are lists of instructions for the processor. Data can be any information that a program needs: character data, numerical data, image data, audio data, and countless other types. The distinction between programs and data is not as clear-cut as you might think, however.

Fundamental Idea: Both programs and data are saved in computer memory in the same way. The electronics of computer memory (both main memory and secondary memory) make no distinction between programs and data.

The insight that both programs and data can be saved using the same electronic methods is one of the most important ideas in computer science. Computer systems can use their memory for whatever needs arise.

Types of Programs

There are two categories of programs. Application programs (usually called just "applications") are programs that people use to get their work done. Computers exist because people want to run these programs. Systems programs keep all the hardware and software running together smoothly. The difference between "application program" and "system program" is fuzzy. Often it is more a matter of marketing than of logic.

Application Programs Systems Programs

Word processors Game programs Spreadsheets Data base systems Graphics programs

Web browsers

Operating system. Networking system. Database system. Programming language software. Web site server.

Data backup.

The most important systems program is the operating system. The operating system is always present when the computer is running. It coordinates the operation of all the hardware and software components of

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the computer system. The operating system is responsible for starting application programs running and finding the resources that they need. When an application program is running, the operating system manages the details of the hardware for it. For example, when you type characters on the keyboard, the operating system determines which application program they are intended for and does the work of getting them there.

Modern operating systems usually come with a user interface that enables users to easily interact with application programs (and with the operating system itself) by using windows, buttons, menus, icons, the mouse, and the keyboard. Examples of operating systems are Unix, Windows 98, Windows NT, Linux, Solaris, and System 7.

Operating Systems

The operating system is a complex collection of many programs concerned with keeping the hardware and software components of a computer system coordinated and functioning. It is like a shop keeper who keeps a shop in order by attending to customers, handling supplier deliveries, stocking the shelves, doing the bookkeeping, and so on.

The operating system is software; the same hardware can be used with many different operating systems (although only one at a time.) Sometimes the operating system on a computer becomes corrupted (perhaps because of a computer virus) and must be tediously re-installed. Until it is up and running again, other programs will not be available.

Starting a Program

When a computer is started up, the hardware will automatically load the operating system and start it running. This process is called booting. The reason for this odd term is that the operating system is itself involved in getting itself running---a process that is like someone "pulling themselves up by their bootstraps." Once the operating system is running, it is used to start up any other program.

Here is a (simplified) list of what happens when the user (you) starts up an application. Assume that the operating system (OS) is already running.

1. The user asks to run an application.o This could be done by clicking on an icon, making a menu choice, or other means.2. The OS determines the name of the application.3. The OS finds the section of the hard disk where the application program and its data are stored.4. The OS finds an unused section of main memory that is large enough for the application.5. The OS makes a copy of the application and its data in that section of main memory.o The software on the hard disk is unchanged; a copy of it has been made in main memory6. The OS sets up resources for the application.7. Finally, the OS starts the application running.

As the application runs, the OS is there in the background managing resources, doing input and output for the application, and keeping everything else running.

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TASK 02

1. New system boards

A motherboard, like a backplane, provides the electrical connections by which the other components of the

system communicate, but unlike a backplane, it also connects the central processing unit and hosts other

subsystems and devices.

A typical desktop computer has its microprocessor, main memory, and other essential components

connected to the motherboard. Other components such as external storage, controllers for video display

and sound, and peripheral devices may be attached to the motherboard as plug-in cards or via cables,

although in modern computers it is increasingly common to integrate some of these peripherals into the

motherboard itself.

An important component of a motherboard is the microprocessor's supporting chipset, which provides the

supporting interfaces between the CPU and the various buses and external components. This chipset

determines, to an extent, the features and capabilities of the motherboard.

Modern motherboards include, at a minimum:

sockets (or slots) in which one or more microprocessors may be installed[3]

slots into which the system's main memory is to be installed (typically in the form

of DIMM modules containing DRAM chips)

a chipset which forms an interface between the CPU's front-side bus, main memory, and

peripheral buses

non-volatile memory chips (usually Flash ROM in modern motherboards) containing the

system's firmware or BIOS

a clock generator which produces the system clock signal to synchronize the various components

slots for expansion cards (these interface to the system via the buses supported by the chipset)

Power connectors, which receive electrical power from the computer power supply and distribute it

to the CPU, chipset, main memory, and expansion cards.[4]

The Octet Jaguar V motherboard from 1993.[5] This board has 6 ISA slots but few onboard peripherals, as

evidenced by the lack of external connectors.

Additionally, nearly all motherboards include logic and connectors to support commonly used input devices,

such as PS/2 connectors for a mouse and keyboard. Early personal computers such as the Apple II or IBM

PC included only this minimal peripheral support on the motherboard. Occasionally video interface

hardware was also integrated into the motherboard; for example, on the Apple II and rarely on IBM-

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compatible computers such as the IBM PC Jr. Additional peripherals such as disk controllers and serial

ports were provided as expansion cards.

Given the high thermal design power of high-speed computer CPUs and components, modern motherboards

nearly always include sinks and mounting points for fans to dissipate excess heat.

2. Processor and memory architecture.(Intel / AMD)

Intel’s new emphasis on low power suits me to a T. The company’s present take on low power is backed with some

specious marketing that pretends the CPU is the only system component that draws current. Even so, Intel earns my

nod for moving its Core micro architecture, the son of a son of a Pentium III, to the top shelf. Core and the rest of

Intel’s road map are not, however, secret weapons that will slice AMD to little bits. AMD is not standing still.

There will always be a need for mainstream CPUs that meet the challenge of “damn the kilowatts, full speed ahead!”

AMD’s Opteron, Athlon FX, Turion, and Athlon X2 CPUs own the high-performance mantle; Intel will not recover it,

and it knows that. Intel is playing on the fact that the coming round of high-performance server and desktop AMD64

processors, due midyear and dubbed Revision F, look like monsters compared with Intel’s tiny Core. AMD64

Revision F uses a bigger die and therefore a bigger socket. Rev F CPUs will consume more power.

Increases in heat and size are unavoidable, given that AMD chose to put a lot more iron inside the chip. But AMD will

put more innovation inside as well, innovation that serves customers now and signals where AMD is likely to go when

it shifts to a 65-nanometer manufacturing process in 2007.

To refresh your memory, today’s dual-core Opteron is an x86-compatible server CPU that comprises a pair of totally

independent cores, each of which is identical to a discrete Opteron processor. Each Opteron core has its own Level 2

cache, an approach that differs from Intel’s shared cache. But Intel’s vaunted shared core advantages are offset by

Opteron’s Direct Connect architecture that runs dedicated Hyper Transport bus links among all cores in a

multiprocessor, multicore server, not just across cores within a single physical CPU. Opteron also incorporates on-

chip memory and I/O controllers, the architectural features that leave Intel in the dust on performance no matter how

fast Intel cranks its FSB (front-side bus) -- the link between CPUs and peripherals -- and memory hub. Opteron has

neither an FSB nor a memory hub. These are not only factors in performance but also in total system power

consumption -- the basis of an honest performance-per-watt analysis -- because Opteron systems are simpler in design

and require fewer components than Intel’s.

AMD is blending a couple of new ingredients into Revision F. The first is an upgrade to Opteron’s on-chip memory

controllers that makes the CPUs compatible with DDR2 memory. That boost will have more impact on Opteron

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performance than Intel’s embrace of DDR2 had on its x86 designs, simply because there’s no glue circuitry between

Opteron CPUs and memory. Intel can implement whatever flavor of memory-to-CPU glue it likes, but as long as it’s

off-chip, much of the performance gain is lost to collisions among CPUs and with I/O traffic. In an Option server,

there is one dedicated memory controller for each physical CPU.

3. Disk drive systems (ATA / SATA)

Parallel ATA (PATA), originally ATA, is an interface standard for the connection of storage devices such

as hard disks, solid-state drives, floppy drives, and optical disc drives in computers. The standard is

maintained by X3/INCITS committee.[1] It uses the underlying AT Attachment (ATA) and AT Attachment

Packet Interface (ATAPI) standards.

The Parallel ATA standard is the result of a long history of incremental technical development, which began

with the original AT Attachment interface, developed for use in early PC AT equipment. The ATA interface

itself evolved in several stages from Western's original Integrated Drive Electronics (IDE) interface. As a

result, many near-synonyms for ATA/ATAPI and its previous incarnations are still in common informal use.

After the introduction of Serial ATA in 2003, the original ATA was retroactively Parallel ATA.

Parallel ATA cables have a maximum allowable length of only 18 in (457 mm). Because of this length limit

the technology normally appears as an internal computer storage interface. For many years ATA provided

the most common and the least expensive interface for this application. It has largely been replaced by Serial

ATA (SATA) in newer systems.

4. Peripherals (USB / Firewire, Bluetooth and Wi – Fi Access)

FireWire Verses USB

While FireWire sounds like USB on steroids, the technologies serve different purposes. FireWire--a much cleaner and more advanced spec than USB--is for peripherals that need maximum bandwidth. USB is a medium bandwidth connection for peripherals such as digital still cameras, monitors, keyboards, and mice.

The crucial feature favoring FireWire is the asynchronous data feature. If you have external data drives (ZIP, Super Disk, Orb, etc.) plugged into the same hub as your printers, scanners and other peripherals, you could have unforeseen trouble. Several Computer User editors have lost data when writing to external drives while printing. Though you can have up to 127 devices daisy chained together, the safe thing to do is use one peripheral at a time. FireWire, on the other hand, allows your peripherals to multitask without risk of data loss.

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But with USB 2.0 looming on the horizon, will FireWire wilt and fade? Not likely. Our prediction is that, even if version 2.0 does what's being promised, the two standards will peacefully coexist into the foreseeable future. It seems doubtful that USB 2.0 will encroach too much on digital video and audio territory that FireWire has slowly but surely conquered.

Why? Because FireWire can transfer data point-to-point (one device to another) while USB requires the computer to serve as a go-between. In other words, moving data with USB means you have to move it from one doohickey to your computer, then transfer it from the computer to the other doohickey. FireWire can move data directly from one device to another. Plus, FireWire will soon hit speeds of 800Mbps, late this year or early in 2001. And there's speculation of speeds of up to 1.6Gbps available a year or two down the road.

With all this in mind, should you choose USB or FireWire peripherals? FireWire is superior in all other ways. All other factors being equal, the only reason to prefer USB over FireWire is price.

With all their extra pizzazz, FireWire peripherals are a bit pricier than their USB cousins. How much? Let's look at two examples: PPS Inc. makes a 4x4x24x CD-RW USB drive that costs about $300. Its closest equivalent with FireWire connectivity costs $100 more, but is 8x4x32x. VST makes an external USB 6GB hard drive that costs $370. Its external FireWire 6GB hard drive is $440.

Still, FireWire is, well, on fire. James Snider, the chairman of the 1394 Trade Association, said the standard is now "exploding" onto the worldwide electronics markets. "1394 will be available on almost 40 percent of all new PCs this year, as the PC expands its role in networking and consumer applications," he said. "All new camcorders made after 2000 will have 1394. Peripherals such as printers, scanners and hard drives are coming out with 1394 now, and digital still image systems represent a very popular application of the technology."

Bluetooth

Bluetooth technology is named after Herald Bluetooth, a Danish king who managed to consolidate Denmark and a part of Norway in the 1900s. The choice for the name of this technology is a manifestation of how influential and central the companies from this region are to the telecommunications industry.

Bluetooth is a networking technology that does not rely on user control or large amounts of power. By keeping the transmission power to an extremely low setting (1 mill watt), Bluetooth is ideal for mobile battery operated devices. Moreover, Bluetooth does not rely on the user since it can automatically detect and communicate with other Bluetooth devices without any user input.

Bluetooth technology relies on two things, a radio frequency technology and the protocol software enabling it to transmit data  to other devices. Bluetooth-capable devices can transmit data to other devices not within the line of sight of the user. It also enables different devices to communicate using certain rules such as the amount of data that will be sent, the type of communication between the devices and the radio frequency or frequencies this communication will take place. These protocols ensure that Bluetooth devices experience the least amount of interference from other Bluetooth capable objects while communicating with each other.

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Wi – Fi Access

Connecting to a wireless network or a wi-fi hotspot is pretty straightforward, though there are differences between different operating systems. This tutorial will help you set up your laptop on Windows XP, Vista/7, or a Mac so you can connect to a wireless network for Internet access or to share files over the network. (The screenshots are from a laptop running Vista, but the instructions have info for the other OSes as well.)Before you get started, you'll need: A wireless network adapter for your laptop (or built-in wireless on a different portable device). If you don't have one built in, you can purchase a USB wireless adapter or a PC card that you just plug in to install. You should also make sure you have a firewall installed and the latest antivirus updates and operating system patches, especially if the network you're connecting to is a public one. (Open wireless networks or ones that just use WEP are really not safe). If the network is secured with a password or the administrators have hidden the network name (SSID) from being broadcast, you'll need to find out that information as well to get connected.

5. Printers (Laser / DeskJet)

Laser Printer

a type of printer that utilizes a laser beam to produce an image on a drum. The light of the laser alters the electrical charge on the drum wherever it hits. The drum is then rolled through a reservoir of toner, which is picked up by the charged portions of the drum. Finally, the toner is transferred to the paper through a combination of heat and pressure. This is also the way copy machines work.Because an entire page is transmitted to a drum before the toner is applied, laser printers are sometimes called page printers. There are two other types of page printers that fall under the category of laser printers even though they do not use lasers at all. One uses an array of LEDs to expose the drum, and the other uses LCDs. Once the drum is charged, however, they both operate like a real laser printer.One of the chief characteristics of laser printers is their resolution -- how many dots (dpi) they lay down. The available resolutions range from 300 dpi at the low end to 1,200 dpi at the high end. By comparison, printing usually prints at 1,200 or 2,400 dpi. Some laser printers achieve higher resolutions with special techniques known generally as resolution enhancement.In addition to the standard monochrome laser printer, which uses a single toner, there also exist color laser printers that use four toners to print in full color. Color laser printers tend to be about five to ten times as expensive as their monochrome siblings.Laser printers produce very high-quality print and are capable of printing an almost unlimited variety of fonts. Most laser printers come with a basic set of fonts, called internal or resident fonts, but you can add additional fonts in one of two ways: Font cartridges  : Laser printers have slots in which you can insert font cartridges, ROM boards on which fonts have been recorded. The advantage of font cartridges is that they use none of the printer’s memory. Soft fonts  : All laser printers come with a certain amount of RAM memory, and you can usually increase the amount of memory by adding memory boards in the printer's expansion slots. You can then copy fonts from a disk to the printer's RAM. This is called downloading fonts. A font that has

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been downloaded is often referred to as a soft font, to distinguish it from the hard fonts available on font cartridges. The more RAM a printer has, the more fonts that can be downloaded at one time.

In addition to text, laser printers are very adept at printing graphics. However, you need significant amounts of memory in the printer to print high-resolution graphics. To print a full-page graphic at 300 dpi, for example, you need at least 1 MB (megabyte) of printer RAM. For a 600-dpi graphic, you need at least 4 MB RAM.Because laser printers are nonimpact printers, they are much quieter than dot or daisy-wheel printers. They are also relatively fast, although not as fast as some dot-matrix printers. The speed of laser printers ranges from about 4 to 20 pages of text per minute (ppm). A typical rate of 6 ppm is equivalent to about 40 characters per second (cps).Laser printers are controlled through page description languages (PDLs) . There are two de facto standards for PDLs: PCL  : Hewlett-Packard (HP) was one of the pioneers of laser printers and has developed a Printer Control Language (PCL) to control output. There are several versions of PCL, so a printer may be compatible with one but not another. In addition, many printers that claim compatibility cannot accept HP font cartridges. PostScript  : This is the de facto standard for Macintosh printers and for all desktop publishing systems.

Most software can print using either of this PDLs. PostScript tends to be a bit more expensive, but it has some features that PCL lacks and it is the standard for desktop publishing. Some printers support both PCL and PostScript.

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DeskJet PrinterA type of printer that works by spraying ionized ink at a sheet of paper. Magnetized plates in the ink's path direct the ink onto the paper in the desired shapes. Ink-jet printers are capable of producing high quality print approaching that produced by laser printers. A typical ink-jet printer provides are solution of 300 dots per inch, although some newer models offer higher resolutions.In general, the price of ink-jet printers is lower than that of laser printers. However, they are also considerably slower. Another drawback of ink-jet printers is that they require a special type of ink that is apt to smudge on inexpensive copier paper.Because ink-jet printers require smaller mechanical parts than laser printers, they are especially popular as portable printers. In addition, color ink-jet printers provide an inexpensive way to print full-color documents.

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TASK 03

In computer networking, topology refers to the layout of connected devices. This article introduces the standard Topologies of networking.

Topology in Network Design

Think of a topology as a network's virtual shape or structure. This shape does not necessarily correspond to the actual physical layout of the devices on the network. For example, the computers on a home LAN may be arranged in a circle in a family room, but it would be highly unlikely to find a ring topology there.

Network topologies are categorized into the following basic types:

bus ring star tree meshMore complex networks can be built as hybrids of two or more of the above basic topologies.

Bus Topology

Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.

Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.

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Advantages of the bus topology

The wiring complexity is low. This factor plays an especially large role in automobiles.

An economical and easy to manage twisted wire pair serves as the transmission medium

CAN stations can be subsequently added to and removed from the existing CAN bus relatively easily. Only the connection to the bus line must be made or disconnected. This aspect plays a significant role, especially with trouble shooting and repairs.

The breakdown of a CAN station has no immediate impact on the CAN bus. All the other stations can communicate unconstrained.

Disadvantages of this bus topology  The bus line cannot be designed arbitrarily long since the electrical properties (e.g. signal reflections) set physical limits in combination with the transmission speed.

The same is also valid for the branch lines to the control units in the automobile. Depending on the transmission speed they may not exceed a certain length.

In order to optimise the signal quality the ends of the bus line must be "terminated" with load resistors. A cable end which is not correctly terminated can make the entire bus inoperative, especially with a high transmission speed.

Ring Topology

In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.To implement a ring network, one typically uses FDDI, SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.

Advantages of Ring topology

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Very orderly network where every device has access to the token and the opportunity to transmit Performs better than a star topology under heavy network load Can create much larger network using Token Ring

Disadvantages of Ring topology

One malfunctioning workstation or bad port in the MAU can create problems for the entire network Moves, adds and changes of devices can affect the network Network adapter cards and MAU's are much more expensive than Ethernet cards and hubs Much slower than an Ethernet network under normal load

Star Topology

Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch orrouter. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.

Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)

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Advantages of the star topology

More suited for larger networks Easy to expand network Easy to troubleshoot because problem usually isolates itself Cabling types can be mixed

Disadvantages of the star topology

Hubs become a single point of network failure, not the cabling Cabling more expensive due to home run needed for every device

Tree Topology

Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.

Advantages of the Tree topology It is the best topology for a large computer network for which star topology or ring topologies are unsuitable due to the sheer scale of the entire network. Tree topology divides the whole network into parts that are more easily manageable. Tree topology makes it possible to have a point to point network. All computers have access to their immediate neighbors in the network and also the central hub. This kind of network makes it possible for multiple network devices to be connected with the central hub. It overcomes the limitation of star network topology, which has a limitation of hub connection points and the broadcast traffic induced limitation of a bus network topology. A tree network provides enough room for future expansion of a network.

Disadvantages of the Tree topology

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Dependence of the entire network on one central hub is a point of vulnerability for this topology. A failure of the central hub or failure of the main data trunk cable can cripple the whole network. With increase in size beyond a point, the management becomes difficult.

Mesh Topology

Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.

A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.

Advantages of the Mesh topology

It has multiple links, so if one route is blocked then other routes can be used for data communication. Each connection can have its own data load, so the traffic problem is eliminated. It ensures the data privacy or security, because every message travels along a dedicated link. Troubleshooting of this topology is easy as compared to other networks. Its performance is not affected with heavy load of data transmission.

Disadvantages of the Mesh topology

It becomes very expensive because a large number of cabling and 110 ports are required. It is difficult to install.

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