Computer Troubleshooting I Guidelines

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Computer

Troubleshooting I

GuidelinesGuide For Newbie’s



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About this book.

This book was developed for the entry-level computer

technician, as well as the experienced technician, who is seeking

certification. For the entry-level students, it starts with the basics and

moves on to more complex topic and subjects. It provides a thorough

understanding of the simple concepts that laid the foundations for

today’s computer.

Features of this book.

Whenever possible, lessons contain procedures that give you an

opportunity to use the skills being presented or explore the part of the

application being described.

Manual by :

For Students Technician

Edited and produced by: Lordevin Cabatlao

Copyright2011

Book Contents



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CHAPTER I: BASICOF

TROUBLESHOOTINGTroubleshooting 1

Introduction to troubleshooting

Fault

Logic Troubleshooting 2

Classical Troubleshooting

Brute Force TroubleshootingSafety of the equipment 4

Basic Troubleshooting

The Basics steps of Troubleshooting 5

Visual Inspection 6

Cleaning the Connections 7

Symptoms AnalysisDiagnose to a Section

Localize to a stage 8

Isolate failed Part Description 9

Don’t Panic.

Observe the conditions.

Use your senses 10

Retry.

Document.

Assume one problem. 11

Use correct technical reference data.

Diagnose to a section (fault identification) 12

Localize to a stage (fault localization)

Isolate to a failed part (fault isolation)

Use correct equipment to aid in the repair.

Repair.

Test and verify proper operation. 13



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CHAPTER II: The Computer CommunicationEarly Communication 13

The Telegraph and Morse Code 14

Parallel and Serial Devices

The Binary Language of the Computer 15

The Three Stages of Computing 16

Processing

Output

Input

CHAPTER III: Components of a ComputerProcessing 18

Input 19

Output 20

CHAPTER IV: The Visible PC: The BeginningThe CPU

24

Processor 26

2 Types of Socket Type Processor 30The Memory 31

Different Types of Memory RAM 32

The Video Card 33

Newer Video Card 38

Motherboard 41

Types of Motherboard 46

AT

Baby AT

ATX

The Back Panel 50

Parts of the Motherboard 52



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CPU 52

Heat Sink 53

Memory Slots / Memory Bank 56Main Power Connector 57

Types of Chipsets 60

The NorthBridge 62

CPU

RAM

Graphic CardsPCI-E

AGP

The SouthBridge 63

On-board graphic cards

IDE

ATAPI

SCSISATA

Ethernet 66

Sound Port 67

CMOS and BIOS 68

The Input and Output 69

Serial Port

Parallel Port 70Keyboard

Mouse 71

Floppy Disk Drive 72

Expansion Slots 73

ISA 74

PCI

PCI-EAGP 75

The Internal Components

CPU 76

Memory

Modem



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Power Supply 77

Types of Power Supply AT and ATX PSU 78

Hard Disk Drive 81Motherboard (Review) 84

CHAPTER I: BASIC OF TROUBLESHOOTINGObjectives

Learn how to identify computer problems Be able to identify components causing problems

Basic problems associated with computer hardware

WHAT IS COMPUTER TROUBLESHOOTING?

Means solving the Computer problems, in a systematic manner,

also known as elimination process of the problem. It is a very

important process especially in the fields of system

administration.

It is based on the process of finding the problem in the simplest

manner.

INTRODUCTION TO TROUBLESHOOTING

PC problems will occur, but you need to know how to confirm

that a failure symptom is really a failure can and not one just an operatorerror or a software bug, software incompatibility can lead one to suspect

a disk drive problem, even when it isn’t. It’s also easy to blame the

computer, but the machine may not be at fault.

FAULT

What is fault? It’s any physical condition that causes an incorrect

output when a circuit is exercised to perform a function. Faults can beclassified as either static or dynamic.

STATIC AND DYNAMIC FAILURES



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Static failures or faults include the stuck-at problems associated

with open and shorted data path in circuitry. These failures are typically

causing system operation to terminate. There are types of statics failures;

Shorts. Can be described as electrical conduction in the

wrong place. Shorts are typically caused by a

mechanical failure in a device or bye solder bridge

during repair.

Opens. Are characterized by a lack of electrical

conduction when it should be present. Electricallyopen inputs can affect the switching speed of a

device and can degrade the noise immunity of the

component. It can be caused by a wrong components by

a wrong components being installed on a board, an

Improperly installed component, a missing component.

Or a dead or partially dead device.

Dynamic failures include time-dependent errors, such as the loss

of signal quality, which causes a circuit output to reach steady state too

late to be properly used by another part of the system. The symptoms of

dynamic faults include devices operating too slow. This failure is seen in

setup-and-hold problems, data and addressing problems, machine cycle-

time instability, and interactive problems between components.

LOGIC TROUBLESHOOTING

The most effective way to locate a failure in an IBM computer is

to approach the problem just the machine operates-logically. Imagine the

computer system as a human body. The timing and the timing circuitry

represent the heart. The CPU and related circuitry are like the brain.

Without the heart and brain, nothing in the body works. The keyboard

and drives represent eyes and ears. The display and printer act like the

mouth. By viewing the computer system as a functioning body system,

quickly determine which area is not working properly and home in on the

malfunctioning part. You need to understand what should happen and

compare the “should,” one by one, with what is really happening.



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There are typically two ways to analyze electronic circuit failures:

1) Classical Troubleshooting incorporating the localizing and isolating of

failures, using deductive reasoning and mental intuition; and 2) BruteForce Troubleshooting utilizing flowcharts and the replacement of all

suspected components. Both techniques will be addressed in this chapter.

COMPUTER TECHNICIANS/IT

It is the troubleshooter responsible for using the right techniques

and solving the problems. A person who repairs and maintains computers and servers.

Technician’s responsibilities may extend to include

building/assembling or configuring new hardware, installing and

updating software packages, and creating and maintaining

computer networks.

SAFETY OF THE EQUIPMENT

Turn off the computer and peripherals.

Disconnect or unplug the equipment.

Touch on the unpainted metal surface on the case / use

grounding wrist or strap.

BASIC TROUBLESHOOTINGSolving computer system problems requires the application of

deductive techniques called “troubleshooting.” Effective and efficient

troubleshooting involves gathering clues and applying the deductive

reasoning needed to isolate a problem. Once you know the cause of a

problem, you can follow a process of analyzing, testing, and substituting

good components for each suspected bad component to find the

particular part that has failed. Good deductive reasoning is used to isolatea failure to a particular group of components or chips. Then, circuit

analysis is used to reduce the problem to a specific component.

In general, there are some optimum steps that you can follow to

successfully troubleshooting and repair a computer.



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1. Don’t Panic.

2. Observe the conditions.

3. Use your senses.4. Retry.

5. Document.

6. Assume one problem.

7. Use correct technical reference data.

8. Diagnose to a section (fault identification).

9. Localize to a stage (fault localization).

10. Isolate to a failed part (fault isolation).11. Use correct equipment to aid in the repair .

12. Repair.

13. Test and Verify.

The following pages discuss in detail the steps necessary for

troubleshooting success.

But first, some cautions and warnings.

Cautions: Modifying or removing components from the circuit boards in

your system may void the manufacturer warranties.

Cautions: Discharge any static electricity present on your body before

troubleshooting or repairing any part of the computer system.

Warning: High Voltages are present inside the power supplies and display

terminals. Unless you are trained in the repair of these units, you should

not try to troubleshoot, or in any way open and work inside either thepower supply or the display monitor.

THE BASIC STEPS OF TROUBLESHOOTING

Now that you understand what is appropriate in troubleshooting

and repairing personal computer, let us proceed.Every computer is composed of functional sections as

diagrammed in Fig. 1.1. Any of these sections can fail. When something

functionally goes wrong in the computer, the first step is to determine

whether the trouble is from an actual failure, such as a loose connection,

or from human error. To do this, you need to understand how the



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computer system works and how it interacts with the other parts of the

system.

Once your convinced that a true component failure has occurred,the next step is to determine which functional section of the system is not

operating – disk drive, keyboard, display, or some other part. To do this,

break each section of the computer or peripheral into stages and trace

the trouble to a circuit stage within that section. Then, analyze the circuit

to isolate the failed part, using the appropriate specific troubleshooting

and repair procedures given in the following chapters.

When troubleshooting a computer, you must discipline yourself to always check that the power switch is in the correct position required

at that time (usually OFF). Make it a practice to always place you hand

over the power switch whenever you first start thinking about doing

something inside the computer. Turn off the power, and then open the

system unit.

VISUAL INSPECTION

There are several specific steps you should take when

troubleshooting an personal system. First, search out all the symptoms –

the clues – that point toward the location of the failure. Make a visual and

operational check of everything that is normally active during operation

of the failing function. Look for loose or incorrectly connected cables and

power cords, switches that are incorrectly set, disk drive doors

inadvertently left open, de-energized wall sockets, and bad disks. Look for

anything that appears out of place.



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Fig. 1.1. The functional units of the Personal Computer of

Microcomputers.

CLEANING THE CONNECTIONS AND SYSTEM UNIT

Turn off the computer and clean all the edge connectors on plug-

in card. Reseat the associated cables, making sure to look for bent pins.

Examine the system board and related interface cards for discoloredcomponents or loose debris. You’d be amazed at what has been found

inside computers, printers, and disk drives. During analysis, I’ve found

pieces of bread, cigarette ashes, stains from coffee spilled in the

keyboard, and even sticky soda pop all over the motherboard. Inside

drives, I’ve found everything from pencils to carrots to dead mice! Don’t



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be surprised by the things that somehow find their way into these

machines.

After checking inside the computer system unit, disk drive, andany other associated equipment, close the system up and reboot. Check

to see if the same failure occurs. If it does, shift to symptom analysis.

SYMPTOMS ANALYSIS

This troubleshooting process involves the examination of

symptoms to determine the area of system failure. If the display screen is

black and shows no sign of video life, check the monitor and video

circuitry and the interconnecting cables. If the program locks up in the

middle of an operation, the failure is most likely in the CPU, ROM, RAM,

or related circuitry. If the drive doesn’t boot, then the drive circuitry, the

disk-drive adapter board, and the related interface cables become

suspect.

When checking symptoms, remember to evaluate all symptoms,

not just ones that seem directly related to the problem. Often other clues

are available.

DIAGNOSE TO A SECTION

Once symptom analysis is completed, narrow the failure down to

a single section. Let’s step through an actual problem example. Suppose

you have a PC that won’t boot the disk in the disk drive. Making a visualcheck, you find that nothing looks amiss, so you analyze the failure

symptom in depth. You notice that when power is applied to the system,

the computer turns on and the power-on self test diagnostics run and

pass without any error message or improper beep emitting from the

speaker. You remember that even though the diagnostics pass, there can

still be a problem in the circuitry tested by the BIOS POST. POST (Power-

on-Self-Test) diagnostics do not test all types of “stuck-at” or impropersignal conditions. In this example, the diagnostics run fine, but when the

drive tries to boot a disk, the system just locks up and doesn’t do things –

yet no failure code is displayed on the screen.

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Turn the computer off and, several seconds later, turn it back on.

Closely watch the action of Drive A. When the BIOS reaches the program

step that tries to load DOS from the disk, the drive light turns on and youcan hear the drive head movement inside. However, several seconds

later, the drive motor stops. The drive light remains on, but no data

seems to be loading from the disk into the system board RAM. A curious

fact. You try another known good disk. Same results. You swap disk drives

and retest. Again, no change. You clean and reseat the drive adapter

board. The you retest. The problem remains. What could be the cause for

this behavior?Removing the disk from the drive, you power the system down

and back up, trying to boot the system up in BASIC. It does. Now that the

CPU, the system board, the screen, and the keyboard sections are

working properly. The problem has been proven to work without the

drives; you conclude that the CPU, the system board, the screen, and the

keyboard sections are working properly. The problem has been reduced

to the disk-drive portion of the system circuitry. Closing in on the failure,you decide that you have a choice to make. (If you have spare cables and

adapter boards, you can swap out one at a time until the problem goes

away. However, if you don’t have spares, you must investigate further.

Look at the magnetic head inside the failing drive as you reapply

power to the system. Upon receiving electrical power, the head should

immediately move to the “home” position farthest from the center of the

hub. This is the location of Track 0. Disk-unique information, such as theboot record, file allocation table (FAT), and directory is located on this

track. In our example, the head goes to the home position. Then, the

moves across the disk just as if it were reading data off a track cylinder

but, a few seconds later, the head movement stops with the head

positioned halfway over the disk surface.



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LOCALIZE TO A STAGE

Check the cable. Then, check the disk-drive controller byswapping the adapter board with another. The problem goes away. The

faulty part has been localized to a circuit stage on the adapter board. In

most problem-analysis procedures, you normally find the problem by this

time. At this point, you must decide if you have the technical experience

to desolder and replace IC’s and other components. Most PC operators do

not have (or even want) this skill.

ISOLATE TO A FAILED PART

You’ve isolated the failure to the adapter board. Further tests

reveal the failed part. If you don’t feel comfortable disordering and

soldering components, the thing to do is purchase a trade-in replacement

board. Or you can send the bad board to a repair shop having the

capability to perform component exchange.

Replacing the part (by whatever means is appropriate), you

restore proper system operation.

THE HARDWARE APPROACH

Usually when a chip comes to the end of its useful life, a

catastrophic failure occurs – it cooks itself internally. Although your eyes

can’t always see the chip defect, you can find the problem without much

effort. (But don’t think that every time your Personal Computer quits

working, you’ve just had a catastrophic failure.) For those problems that

are not easy to identify. Let’s refer again to our guidelines for success.

1. Don’t Panic.

2. Observe the conditions.

3. Use your senses.4. Retry.

5. Document.

6. Assume one problem.

7. Use correct technical reference data.

8. Diagnose to a section (fault identification).



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9. Localize to a stage (fault localization).

10. Isolate to a failed part (fault isolation).

11. Use correct equipment to aid in the repair.12. Repair.

13. Test and verify proper operation.

Don’t Panic

Besides your user’s and reference manuals, you now have a book

that will help.

ObserveWhat are the symptoms? What conditions existed at the time of

failure? What actions were in progress? What program was running?

What was on the display screen? Was there an error message? What

functions still work?

Use Your Senses

Look and smell. Is there any odor present that suggests

overheated components? Does any part of the system feel hot? Do any

components look charred or broken?

Retry

If the display monitor is dark, check its brightness control, the

power plug, and the power cord. Is the plug inserted snugly into the back

of the computer? Is other end of the power cord plugged into a wall

socket? Is the wall socket working? One AT system “failure” turned out to

be the 115/220 switch on the computer. If any of these items aren’t all

right, fix them and try again.

If the problem involves an external display, the printer, or other

I/O peripherals equipment connected to the computer by cable, confirms

that the power to the system Is turned off. Then disconnect the power

plug from the computer retighten all of the connector cables associated

with the failure. Cables have a habit of working loose if they aren’t

clamped down. Most cables have screw-in hold-downs, or the socket

without making sure that it stays mated. Once you’ve checked the cable

connections, reconnect the power plug, power up, and retry.

If a disk won’t boot, try booting the disk in the other drive (if

there is another floppy drive), or try booting another copy of the program



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disk. You could also try booting the disk in another compatible PC.

(Always use a copy of the program disk. Then, any disk-drive failure won’t

cause as much frustration if it destroys the data on the backup disk as itwould if the disk in use were the program masters. Also, if data are

altered by a malfunctioning drive, the disk can be recopied again from the

program master once the drive problem is resolved.)

Document

Document everything you see, sense, and do. Write down all the

conditions observed at the time of failure, or when you verified areported failure. Write down the conditions that exist now.

What is the PC doing?

What is it not doing?

What is being displayed on the monitor?

Is there an error message?

What is still operating with everything connected? With

everything but the monitor disconnected

Is power still indicated on each part of the system?

Assume One Problem

In digital circuitry, the likelihood of multiple simultaneous

failures is low. Usually a single chip malfunctions, causing one or more

symptoms. However, if you’ve shorted something in the circuitry, all bets

are off.

Use Correct Service Data

Even a do-it-yourselfer needs good information. You’d be

amazed at how many “Mom and Pop” service centers try to run repair

operations with little or no technical information on the equipment they

claim to support. In one case, a service center covering an entire state

was conducting repair activities on a myriad of personal computers, using

a 20-page “Technical Manual” and one of my troubleshooting and repair

guides. The manufacturers technical manual was so poor, it was

essentially useless. And, while the Howard W. Sams & Company micro-

maintenance series of troubleshooting and repair guides are good, they

are high-level overview descriptions of personal computer equipment and



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do not provide information on measurements, waveforms, dc voltages,

and in-depth technical theory of operations. This information can be

found in advanced types of troubleshooting and repair manuals, themanufacturer’s technical repair manuals, and the Howard W. Sams &

Company COMPUTERFACTS on the IBM, PC, IBM PC/XT, and IBM PC AT.

You can go only so far using this book. Don’t attempt a detailed

repair without additional service data. If this is your intent, make sure

that you have appropriate Sams COMPUTERFACTS and an advanced

troubleshooting and repair manual on hand, and also anything the

manufacturer can or will provide. The use of correct and complete serviceinformation can prevent moderately difficult repair jobs from becoming

“tough dogs.” If you value your time, prepare before your repair.

Use Proper Test Equipment

If you intend to go after the “dogs,” use the right test equipment.

Just like the proper technical documentation, the right test equipment

can change difficult repair jobs into routine activities. Going after a failurein electronic circuitry when you are inadequately prepared is like tracking

a rabbit through your garden with your eyes blindfolded. Your actions

make little difference and, all while, that rabbit eats more and more of

your garden away. The use of proper equipment will be discussed in

greater detail later in the book.

Diagnose to the SectionIf the system worked when the peripherals were disconnected

(step 4), turn the power off and reconnect one of the peripherals. Power

up and test. If the unit still works, turn the power off, and reconnect

another peripheral. Again, power up and test. Follow this procedure until

the unit fails. The built-in diagnostic tests are a big help here. Once a

failure occurs, you know what device ad what interface section has the

problem.If you disconnected all the peripherals in step 4 and tested the

computer alone, and it still didn’t work, try to determine what section or

division of the machine failed. Describe the failure in simple terms – Drive

B won’t read a disk. Drive A will.



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Consult the Symptom Index

The machine-specific troubleshooting procedure in the

following chapters contains an index or chart of the most commonfailure symptoms associated with the Personal Computers. Each of

these chapters includes a section on system error displays. If any error

codes are displayed, translating these codes properly can guide you to

the correct area of the problem. If the trouble symptoms match a

problem described in the pertinent troubleshooting index, turn to the

referenced page and follow the instructions given.

CAUTIONS: Any time you open the computer, ensure that the power is

off. Then, touch a metal lamp, or other grounded object, to remove anystray static electricity that might be on your body.

Localize To A Stage

Turn off the power to the computer, and disconnect the power

plug. Disassemble the computer. Follow the detailed circuit

troubleshooting and analysis steps and procedures given in the following

chapters to localize to the failed stage.

Isolate To The Failed PartClosely following the detailed circuit troubleshooting and

analysis procedures given in the following chapters should guide you to

the failed part.

The Telegraph and Morse Code

Telegraphs and early radio communication used a common code for

transmissions. Morse code, named after its creator, Samuel F.B. Morse, is based on

assigning a series of dots (short pulses) and dashes (long pulses) to represent each letter of

the alphabet. These pulses are sent over a wire in a prescribed series. The operator on the

receiving end would generally use a “code book” to interpret the code back into letters and

words. (Of course experienced operators became familiar with the code and could interpret

each character from memory.)

Today’s computers are similar to the early telegraph – they both transmit

information over a wire in a digital fashion using a special code. However, the telegraph’s

primary function was to communicate over long distances while the computer

communicates internally. Another big difference is that computers use more than one wire

and a different type of code (based on multiple wires).



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Parallel and Serial Devices

In modern terms, the telegraph could be described as digital

serial communication devices. It is digital because it uses some discrete

(on/off) code and serial because it sends each piece of information one

bit at a time. If we create a code in which each letter of the alphabet

represents some combination of eight pieces of digital information (ons

or offs), and we send each piece of information one at a time, we are

communicating with a digital serial device. This form of communication

works well (if we have only one wire), but it’s slow because we have to

send eight pieces of information one after the other to represent one

piece of information (a letter of the alphabet). But, what if, instead of one

telegraph wire, we had eight? Now we could send all eight pieces of

information at the same time or in parallel. This is precisely how a

computer communicates. Figure 1.2



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Serial Parallel

Figure 1.2 Serial and Parallel Communication

THE BINARY LANGUAGE OF COMPUTERS

Computers are machines. In order for them to communicate,they need a language of their own. Computer language is called binary;

it’s based on something either being on or off.

Bits

A bit is the smallest unit of information that is recognized by a

microcomputer. It is similar to a light bulb since it can exist only in twostates – it is either on or it is off. A bit is the method used for transmitting

information on a single wire telegraph system.

Bytes

A byte is a group of eight bits. A byte is required in order to

represent once character of information. Pressing one key on a keyboard

is equivalent to sending one byte of information to the CPU (thecomputer’s Central Processing Unit). A byte is the standard unit of

measuring memory in a microcomputer – values are expressed in terms

of kilobytes (KB) or megabytes (MB). The following table lists units or

computer memory and their values.



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Bit Smallest unit of information, shorthand term

for binary digit.

Nibble 4 bits. (Half of a byte.)Byte 8 bits. (One character equals 8 bits.)

Word 16 bits on a computer. (Larger computers can

use words that are up to 64 bits long.

Kilobyte(KB) 1024 bytes.

Megabyte(MB) 1,048,576 bytes. (Approximately one million

bytes or 1024 kilobytes.)Gigabyte 1,073,741,824 bytes (Approximately one billion

bytes or 1024 megabytes.)

Terabyte 1, 099, 511, 627, 776 bytes (Approximately one

trillion bytes or 1,024 gigabytes.)

Binary

As previously mentioned, a bit can exist in only two states, on

and off. When bits are presented visually:1 (one) equals on

0 (zero) equals off

THE THREE STAGES OF COMPUTING

In this lesson, you will take a look at what makes up the three

stages of computing

After this lesson, you will be able to:

Describe the three stages of computing.

A modern compare may look like a complicated device. It is

made up of many components connected with what seems to be miles of

interlocking wires. Despite this seeming complexity, however, just like a

calculator, a computer handles information in three stages: input,

processing, and output (see Figure 1.3.) Each piece hardware can be

classified in one (and sometimes two) of three stages.



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Figure 1.3 Three Stages of Computing

Processing

Although processing is the second stage of computing, we’ll start

here because these components are heart of the computer. Computers

were initially designed for business environment; they were intended as

tools to do the tedious work of “number crunching” and storing large

amounts of often redundant data. Today they not only fulfill an ever-

expanding business role, but also fill our lives with education,

entertainment, organization, information processing, and, occasionally,

frustration. As we enter a new century, they have become a necessity of

life and may soon be taken for granted. Even if you do not own or use a

computer, microprocessor run most mechanical and electronic devices,

including cars.

Input

The ability to process data is a great and wondrous thing.

However, if the data cannot find its way into the processor, nothing will

happen. The first stage of a computer is input. Input refers to any means

that moves data (information) from the outside world into processor.



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Output

All input and processing in the world won’t do us any good

unless we can get the information back (after being processed) so that wemay put it to use. The third stage of computers is output.

Input, Output, and Processing

Whenever you sit down at a computer and run an application,

whether it is a game, a spreadsheet, a database, or a word processor, you

are an active part of the input, processing, and output operation of that

computer. The following table provides some examples.

Word Processor Input: Words you type.

Processing: Formatting the text (word-

wrap, fonts and so on).

Output: Storing the text and letting

you retrieve or print it.

Spreadsheet Input: Numbers (such as sales figures)you type or provide.

Processing: Applying one or more

formulas to the data.

Output: Showing the results of the

calculation in numeric or graphical

form.

Database Input: Typing information into a data form.

Processing: Indexing and storing the data

records.

Output: Reports showing selected data

records.

Game Input: Moving your chess piece.

Processing: The computer figures out how torespond to your move.

Output: The computer’s move.



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CHAPTER III: Components of a Computer

Objective

To define the components that makes up a

computer.

To acknowledge and familiarize the computer

parts.

As you might expect, the components of a computer reflect the

function of the machine; specifically, the three stages of computing, as

outlined in Chapter II.

Processing

The CPU (Central Processing Unit) is the heart and brain of the

computer. This one component or “chip” does all the number crunching

and data management. It is truly the centerpiece of any computer. It is so

important that whole generations of computer technology are based and

measured on each “new and improved” version of the CPU.

When we refer to the CPU, we are generally speaking of the

processor. But the CPU actually encompasses several other components

that support it with the management of data. These components, when

working in harmony, make up the computer we know today. The

following table lists these components.



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Components Description

Motherboard


Chip set

Data Bus

The large circuit board found inside the computer.

Without this, a computer is just a box. The

motherboard contains all the following items in

this table and, for all practical purposes, “is the

computer.”

A group of computer chips or IC’s (integrated

circuits) that, when working in harmony,

manage and control the computer system. This

set includes the CPU and other chips that

control the flow of data throughout the

system.

A group of parallel conductors (circuit traces)

found on the motherboard. It is used by the CPU

to send and receive data from all the devices inthe computer.



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Address Bus

Expansion Slots

Clock

Battery

A group of parallel conductors (circuit traces)

found on the motherboard that are used by the

CPU to “address” memory locations. Determines

what information is sent to, or received from, the

data bus.

Specialized sockets that allow additional devices

(circuit boards) to be attached to the

motherboard. They are used to expand or

customize a computer. They are an extension of

the computer’s bus system.

Establishes the maximum speed at which the

processor can execute commands. Not to be

confused with the clock that keeps time.

Prevents unique information about the setup

of the computer from being lost when thepower is turned off. Also maintains the

external clock time (not to be confused with

the CPU’s clock).



P a g e | 27


Memory

InputThe following table lists the devices that are used

exclusively to get information into the CPU.


Keyboard

Mouse

Scanner

Microphone

CD-ROM

Stores Temporary information (in the form of data

bits) that the CPU and software need to keep

running.

Used with graphical interface environments to point

and select objects on the system’s monitor. Can

purchased in a variety of sizes, shapes, andconfigurations.

Converts printed or photographic infor-

mation to digital information what can be

used by the computer. Works similar to the

scanning process of a photocopy machine.

Just like the microphone on a taperecorder. Allows input of voice or music to

be converted to digital information and

saved to a file.

Compact Disc-Read Only Memory: A devices that

allows to read disc and store data to the computer.

Stores Temporary information (in the form of

data bits) that the CPU and software need to keep

running.



P a g e | 28

Output

The following table list the common devices used exclusively for

ouput.


Monitor

The primary output

device. Visually

displays text and

graphics.

Plotter

Speaker

Printer


Web Cam A webcam is a video camera which feeds its images in real ti

computer or computer network, often via USB, ethernet or

you to see while chatting.

Similar to a pointer, but uses

pens to draw an image. Most

often used with graphics ordrawing programs.

Reproduce sound. Optional high-

quality speakers can be added to

provide improved output from

games and multimedia software.

Generates a “hard copy” of information.



P a g e | 29

Input / Output (I/O)

Many devices can handle both input and output functions.

These devices are called I/O devices, a term you will encounter

quite often.


Modem

Hard Disk Drive

Floppy Drive

Network Card

Worm CD

Converts computer data to information that can

be transmitted via telephone wires and cable

lines. Allows communication between computers

over long and short distances.

High-capacity internal (and sometimes

external) magnetic disks for data storage

and program files. Also called fixed disks.

Mechanism to read and write to low-capacity,

removable, magnetic disk. Used to store and

easily transport information.

An expansion card that allows several

computers to connect to each other and share

information and programs.

Also called CD/R – a version of CD that allowsthe user to write once read many. You can

create a CD with this device, but you can only

write to it once. Currently these devices are

slow and expensive. The latest technology is the

CD-RW (CD Write/Read). This product will allow

you to read, write and overwrite a special CD-

ROM disk.



P a g e | 30

THE SUPPORT HARDWARE

After this lesson, you will be able to:

Identify additional support hardware for a

computer.

Understand the function of some of the add-on

hardware.

In addition to the devices that support the dataprocessing functions of a computer; there are others that

enhance its operation and performance. The following

table lists some of here.


Power Supply

Switch Box

Surge Suppressor

UPS

Converts a local power source (typically 110 volts

AC) to 5 and 12 volts DC.

Allows the user to manually (or automatically) switch cab

connections so that one computer can use several printe

or devices .with one parallel port.

Used to prevent large power spikes (for instance,

lightning) from damaging a computer.

Uninterruptible Power Supply – Acts as both a surg

suppresser (to prevent high power spikes) and a powe

leveler to provide the computer with a constant sourc

of power. May even provide power during a powe

failure or interruption (although the duration depend

on the UPS and the computers power consumption) s

the user can safely save data before shutting down.



P a g e | 31

CHAPTER

The Visible PC

The Beginning

IV



P a g e | 32

Objective

In this chapter, you will:

See the major components of a PC.

Understand the different connectors in a PC.

Recognize the most common cards in a PC.

Sometimes, in order to understand the details, you first need to

understand the big picture. This chapter’s job is to allow you to

understand the function and recognize the main components of the CPU.

You will also see all the major connectors, plugs, and sockets, and be able

to recognize a particular part by simply seeing what type of connectors is

attached to that part. Even if you are an expert, don’t skip this chapter! It

introduces a large number of terms that will be used throughout the rest

of the book guide. Many of these terms you will know but some you

won’t so take some time and read it.

THE CPUThe CPU (Central Processing Unit, also called the microprocessor)

is where all the calculations take place in a PC. CPU’s some in a variety of

shapes and sizes (Figure 1.4). The most common in today’s PC are LGA

(Land Grid Array) replacement of PGA (Pin Grid Array) and SEC (Single

Edge Cartridge).

Modern CPUs generate a lot of heat. To cool the CPU, a cooling

fan or a heatsink is attached (Figure 1.5). This cooling device is usually

removable although some CPU manufacturers sell the CPU with fan

permanently attached.

CPUs have a make and model, just like an automobile. When

talking about particular car, most people speak in terms of a “mustang” or

a “BMW”. When they talk about CPUs, they say, “Intel 2Core CPU or Dual

Core” or a “Core2Quad CPU or QuadCore” or an “AMD Athlon x64”. Some

of the more common makes are AMD, Cyrix, and Intel. Now some of the

common models are Intel Pentium IV “Socket 478”, Athlon AMD “Socket

462”. In early years of CPUs, makers would sometime make the exact

same model, so you could get an Intel Sempron, Intel 2 Core CPU, Intel

Core2Duo, and Intel Core2Quad. Not like in first CPU history we have



P a g e | 33

8088, 286, 386, 485, Pentium Pro, K5, K6, and 6x86 which is now is very

rare and also face out.

Figure 1.4

Typical CPU

Figure 1.5



P a g e | 34

Installed CPU under a HeatSink with Fan

PROCESSOR

The CPU is centrally located on the motherboard. Since the CPU

carries out a large share of the working the computer, data pass

continually through it. The data come from the RAM and the units

(keyboard, drives, etc.). After processing, the data is sent back to the RAM

and the units. The CPU continually receives instructions to be executed.

Each instruction is a data processing order. The work itself consists mostly

of calculations and data transport.

Processor types of performing a process in a computer which is;

ARITHMETIC-LOGIC UNIT

The arithmetic-logic unit (ALU) performs all arithmetic

operations (addition, subtraction, multiplication, and division) and logic

operations. Logic operations test various conditions encountered during

processing and allow for different actions to be taken based on the

results. The data required performing the arithmetic and logical functions

are inputs from the designated CPU registers and operands. The ALU

relies on basic items to perform its operations. These include number

systems, data routing circuits (adders/subtracters), timing, instructions,

operands, and registers.

Typically, the ALU has direct input and output access to the

processor controller, main memory (random access memory or

RAM in a personal computer), and input/output devices.‡Inputs

and outputs flow along an electronic path that is called a bus

The input consists of an instruction word (sometimes called a

machine instruction word) that contains an operation code(sometimes called an "op code"), one or more operands, and

sometimes a format code.

The operation code tells the ALU what operation to perform and

the operands are used in the operation. (For example, two operands



P a g e | 35

might bead together or compared logically.) The format may be combined

with the op code and tells, for example, whether this is a fixed-point or a

floating-point instruction. The output consists of a result that is placed instorage register and settings that indicate whether the operation was

performed successfully. (If it isn't, some sort of status will be stored in a

permanent place that is sometimes called the machine status word.)

Control Unit

The control unit maintains order within the computer system

and directs the flow of traffic (operations) and data.

The control unit directs the entire computer system to carry out

stored program instructions.

The control unit must communicate with both the arithmetic logic

unit and main memory.

The control unit uses the instruction contained in the Instruction

Register to decide which circuits need to be activated. The control unit co-ordinates the activities of the other two units as

well as all peripheral and auxiliary storage devices linked to the

computer.

The control unit instructs the arithmetic logic unit which arithmetic

operations or logical operation is to be performed. The control unit is

literally in control.

FPU Floating Point Unit

Performs division and large decimal operations.

Cache Memory

Predicts and anticipates the data that the processor needs.

I /O Unit: Input Output unit.

The gateway for the processor.

How the CPU Works



P a g e | 36

The CPU is centrally located on the motherboard. Since the CPU

carries out a large share of the working the computer, data pass

continually through it. The data come from the RAM and the units(keyboard, drives, etc.). After processing, the data is sent back to the RAM

and the units.

The CPU continually receives instructions to be executed. Each

instruction is a data processing order. The work itself consists mostly of

calculations and data transport.

Processor Types

The Slot Type

Slot type processor is also known as Single Edge Contact Cartridge

(SECC). Is a processor cartridge that plugs into a motherboard on Slot 1. SECC was

designed to hold the Intel Pentium II as well as external cache. SECC was replaced

with the newer SECC2 technology that was designed to hold the Intel Pentium II

450 and Pentium III. See Figure 1.6

Figure 1.6

The Socket TypeMotherboards are subcategorized by the type of processor socket they

have. The processor socket (also called a CPU socket) is the connector on the

motherboard that houses a CPU and forms the electrical interface and contact

with the CPU. Processor sockets use a pin grid array (PGA) (see fig. 1.7) where pins

on the underside of the processor connect to holes in the processor socket.

Computers based on the Intel x86 architecture include socket processors. Now we

have the newest socket which is (LGA) Land Grid Array (see fig. 1.8.) Socket T

supports Pentium 4, Celeron, Core 2 and Quad Xeon. Using the word socket inconnection with LGA775 is somewhat misleading. Traditionally CPU sockets

contain holes that pin on the underside of the CPU it contacts with. However, with

the LGA775 there are no holes, but instead 775 pins protrude from the CPU

socket that makes contact with points on the underside of the CPU.



P a g e | 37

PGA (Socket 478) LGA (Socket T or

LGA775)

Figure 1.7 Figure 1.8

2 Types of Socket Type Processor

PGA (Pin Grid Array)

A pin grid array, often abbreviated PGA, is a type of integrated

circuit packaging. In a PGA, the package is square or roughly square and

the pins are arranged in a regular array on the underside of the package.

The pins are commonly spaced 2.54 mm (0.1") apart, and may or may not

cover the entire underside of the package. See Fig. 1.9.

PGAs are often mounted on printed circuit boards using the

through hole method or inserted into a socket (See figure 2.0). PGAs allow

for more pins per integrated circuit than older packages such as dual in-

line package (DIP).

Pin Grid Array CPU PGA CPU Socket

Figure 1.9 Figure 2.0



P a g e | 38

LGA (Land Grid Array)

The land grid array (LGA) is a type of surface-mount packaging

for integrated circuits (ICs) that is notable for having the pins on thesocket rather than the integrated circuit. An LGA can be electrically

connected to a printed circuit board (PCB) either by the use of a socket or

by soldering directly to the board.

LGA is used as a physical interface for microprocessors of the

Intel Pentium 4 (Prescott), Intel Xeon, Intel Core 2, Intel Core (Bloomfield

and Lynnfield) and AMD Opteron families. Unlike the pin grid array (PGA)

interface found on most AMD and older Intel processors, there are nopins on the chip; in place of the pins are pads of bare gold-plated copper

that touch pins on the motherboard. (See Fig. 2.1)

LGA CPU Socket Land Grid Array CPU

LGA775

Pentium 4 Prescott CPU

Figure 2.1



P a g e | 39

THE MEMORY RAM

A computer requires a memory to store and retrieve instructions

and data. There are a variety of storage devices including semiconductor

or memories and magnetic memories. Generally, the term memory refers

to only the small integrated circuits called chips, which are used as a

computer's internal memory.In computing, memory refers to the state information of a

computing system, as it is kept active in some physical structure. The term

"memory" is used for the information in physical systems which are fast

(RAM), as a distinction from physical systems which are slow to access

(data storage). By design, the term "memory" refers to temporary state

devices, whereas the term "storage" is reserved for permanent data.

Advances in storage technology have blurred the distinction a bit —memory kept on what is conventionally a storage system is called "virtual

memory".

Random-access memory (RAM) is a form of computer data storage.

Today, it takes the form of integrated circuits that allow stored data to be

accessed in any order in a constant time, regardless of its physical

location and whether it is related to the previous piece of data. RAM is

often associated with volatile types of memory (such as DRAM memory

modules), where its stored information is lost if the power is removed.

Many other types of non-volatile memory are RAM as well, including

most types of ROM and a type of flash memory called NOR-Flash. The first

RAM modules to come into the market were created in 1951 and were

sold until the late 1960s and early 1970s. However, other memory devices

(magnetic tapes, disks) can access the storage data in a predetermined

order, because mechanical designs only allow this.



P a g e | 40

RAM (random –access memory) is where the CPU stores

programs and data it is currently using. RAM is measured in units called

bytes. Modern PCs have many millions of bytes of RAM, so RAM ismeasured in units called Megabytes. An average PC will usually have

anywhere from 8 megabytes to 64 megabytes of RAM, although it can

easily be more or less. RAM has been packaged in many different ways

over the years. The two most current packages are called SIMMs (single

inline memory module) and DIMMs (dual inline memory module). See fig

2.2

Figure 2.2

There are many different sizes of SIMMs and DIMMs. The two

most common sizes of SIMMs are 30-pin and 70-pin SIMM is much larger

than the 30-pin SIMM. 72-pin SIMMs are more modern and are designedto hold more RAM than 30-pin SIMMs. 72-pin SIMMs can also transfer

information to and from the CPU faster than 30-pin SIMMs. There are also two

different sizes of DIMMs used by PCs: 168-pin DIMMs are commonly used in

today’s desktop PCs.

Different Types of Memory RAM

DRAM -- Dynamic RAM

Dynamic random access memory (DRAM) is the most common

kind of random access memory (RAM) for personal computers and

workstations. Memory is the network of electrically-charged points in

which a computer stores quickly accessible data in the form of 0s and 1s.



P a g e | 41

Random access means that the PC processor can access any part of the

memory or data storage space directly rather than having to proceed

sequentially from some starting place. DRAM is dynamic in that, unlikestatic RAM (SRAM), it needs to have its storage cells refreshed or given a

new electronic charge every few milliseconds. Static RAM does not need

refreshing because it operates on the principle of moving current that is

switched in one of two directions rather than a storage cell that holds a

charge in place. Static RAM is generally used for cache memory, which

can be accessed more quickly than DRAM.

DRAM stores each bit in a storage cell consisting of a capacitorand a transistor. Capacitors tend to lose their charge rather quickly; thus,

the need for recharging. A variety of other RAM interfaces to the

computer exist, such as EDO RAM and SDRAM.

RDRAM -- Rambus DRAM (See Fig. 2.3)

Rambus Dynamic Random Access Memory

Fig. 2.3

If you are using RDRAM, make sure that all memory sockets of a

channel are filled with either a memory chip or a continuity module.

RDRAM often has to be installed in pairs of the same type of

memory chips. RDRAM devices may be configured into single-, dual- or

quad-channel RIMM modules. For dual-channel or quad-channel (4-

channel) RDRAM chipsets and motherboards, memory module upgrades

should be in matched pairs. For instance, to add 512 MB of memory into a

dual or 4-channel system, two matched 256 MB modules should be inserted.

32-bit RIMM modules, such as RIMM 4200, 4800, and 6400 modules,can be upgraded singly on dual channel systems.

SDRAM -- Synchronous DRAM (See Fig. 2.4)



P a g e | 42

Synchronous Dynamic Random Access Memory

SDRAM – 168 Pin

Fig. 2.4

SDRAM (synchronous DRAM) is a generic name for various kinds

of dynamic random access memory (DRAM) that are synchronized with

the clock speed that the microprocessor is optimized for. This tends to

increase the number of instructions that the processor can perform in a

given time. The speed of SDRAM is rated in MHz rather than in

nanoseconds (ns). This makes it easier to compare the bus speed and the

RAM chip speed. You can convert the RAM clock speed to nanoseconds by

dividing the chip speed into 1 billion ns (which is one second). For

example, an 83 MHz RAM would be equivalent to 12 ns.

Example: PC-133 CL2 SDRAM = 133MHz (SDRAM, PC133 • CL=2 •

Unbuffered • Non-parity • 133MHz • 3.3V)

DDR SDRAM -- Double Data Rate SDRAM (See Fig. 2.5)

DDR1 – 184 pin

Fig. 2.5

DDR SDRAM is synchronous dynamic RAM (SDRAM) that can theoretically

improve memory clock speed to at least 200 MHz*. It activates output on

both the rising and falling edge of the system clock rather than on just the

rising edge, potentially doubling output. It's expected that a number of Socket 7

chipset makers will support this form of SDRAM.

When released DDR SDRAM memory was about twice as expensive as

conventional SDRAM memory.

*Synchronous DRAM speed is measured in MHz rather than nanoseconds (ns).

You can convert the RAM clock speed to nanoseconds by dividing the chip speed



P a g e | 43

into 1 billion ns (which is one second). For example, an 83 MHz RAM would be

equivalent to 12 ns.

Examples:

PC-4000 = DDR-500

PC-3200 = DDR-400 *

PC-2700 = DDR-333 (DDR333)*

PC-2100 = DDR-266 (DDR266)

PC133

PC100 = PC-100 DDR RAM was sometimes called PC-1600SDRAM because of its data bandwidth (transfer capacity) of

1.6GB per second.

*comes in 184-pin DIMM and 200-pin SODIMM formats

The first official platform with DDR SDRAM support was released in

October 2000. Also known as Dual Dynamic Random Access Memory or

DDRAM.

DDR2 SDRAM -- Double Data Rate SDRAM or Dual Dynamic Random

Access Memory

Examples:

DDR2 PC2-3200 = DDR2-400

DDR2 PC2-4300 = DDR2-533

Figure: Marketing-based comparison of DDR types, in Gigabytes

per second. (figure2.6)

Fig. 2.6



P a g e | 44

Classification of DDR2

DDR 2 RAM was evolved from the SDRAM category. From SDRAM, the

memory evolved to DDR RAM in two years and from that to DDR2 Ram inthe next two years.

Since DDR reads data on both the rising and falling edges of the time

clock, the DDR module can transfer data twice as fast as the SDR module.

This is the main difference between SDR and DDR Ram modules. See Fig.

2.7

A 240 pin DIMM (Dual Inline Memory Module) is the new form

factor for DDR 2 RAM and DDR2 RAM will also be available at 533MHz

DDR, 667MHz DDR and 800MHz DDR specifications in the future.

THE VIDEO CARD

The video card, or display adapter, is the brain of the PCs video

(see fig. 2.8). The video card is composed of two major pieces: the video

RAM and the video processor circuitry. The video RAM is where the video

image is stored. On the first video cards, this RAM was just good old

DRAM, just like the RAM on the motherboard. The video processingcircuitry takes the information on the video RAM and shoots it out to the

monitor.

The trick to understanding video cards is to appreciate the

beginnings and the evolution of video. Video output to computers has



P a g e | 45

been around long before PCs were created. At the time PCs became

popular; video was almost exclusively text-based. By text, I mean that the

only image the video card could place on the monitor was one of the 256ASCII characters. These Character were made up of patterns of pixels that

were stored in the system BIOS, which stored the image of that character

onto the video memory. The character then appeared on the screen.

The beauty of text video cards was that they were simple to use

the cheap to make. The simplicity was based on the fact that there were

only 256 characters, and there were no color choices – just monochrometext (figure 2.9). You could, however, choose to make the character

bright, dim, normal, underlined, or blinking. It was easy to position the

characters, as there was space on the screen for only 80 characters per

line and 24 lines.

16bit ISA Blaster Video CardFigure 2.8



P a g e | 46

DOS Program

Figure 2.9

A video card, video adapter, graphics accelerator card, display

adapter, or graphics card is an expansion card whose function is to

generate output images to a display. Most video cards offer added

functions, such as accelerated rendering of 3D scenes and 2D graphics,

video capture, TV-tuner adapter, MPEG-2/MPEG-4 decoding, FireWire,

light pen, TV output, or the ability to connect multiple monitors (multi-

monitor). Other modern high performance video cards are used for more

graphically demanding purposes, such as PC games. See Figure 3.0

Video hardware can be integrated on the motherboard. Howeverlimitation to this integrated graphics chip often only occurs with early

machines. In this configuration it is sometimes referred to as a video

controller or graphics controller. Modern low-end to mid-range

motherboards often include a graphics chipset developed by the

developer of the Northbridge (i.e. an nForce chipset with Nvidia graphics

or an Intel chipset with Intel graphics) on the motherboard. This graphics

chip usually has a small quantity of embedded memory and takes some of the system's main RAM, reducing the total RAM available. This is usually

called integrated graphics or on-board graphics, and is low-performance

and undesirable for those wishing to run 3D applications. A dedicated

graphics card on the other hand has its own RAM and Processor

specifically for processing video images, and thus offloads this work from



P a g e | 47

the CPU and system RAM. Almost all of these motherboards allow the

disabling of the integrated graphics chip in BIOS, and have an PCI, AGP, or

PCI Express slot for adding a higher-performance graphics card in place of the integrated graphics.

Star Wars Forced Unleashed 2

Figure 3.0

Based on what you see and what you know so far, it would seem as though there

were different type of video cards: monochrome text, color text, monochromegraphics, and color graphics. Any PC might want to do more than one of these;

you might want to start with a text mode and then switch into color graphics. So

what are you going to do? – keep two video cards in the PC and then switch the

cable? Of course not. Instead, one video card can be all of the previously defined

video cards in one. A modern video card can act as more than one type of card,

displaying text or graphics monochrome or color, as needed. As different types of

video cards are discussed in the next few sections, I will list the modes associated

with each type.

MDA

The first video card ever produced with the IBM PC was the text-

only Monochrome Display Adapter (MDA). An MDA is perfectly fine for



P a g e | 48

DOS – based word-processing and spreadsheet programs. The MDA has a

9-pin female socket and is found only in the most ancient of PCs and

landfills. Resolution: 80x25, Type: text, Color: Mono

CGA

The IBM PC offered the first-generation color monitor, the Color

Graphics Adapter (CGA) Card, which supports colors but does so at a

prices: resolution. A four color screen offered only 320x200 resolution. It

was possible to support 640x200 resolution, but the number of available

colors dropped to only two. Like its less-gifted older siblings, it also uses a

9-pin male connector.

EGA

The Enhanced Graphics Adapter (EGA) was introduced late 1984

as an improvement on the CGA standard. It could support a resolution of

up to 640x350 with 16 colors in text mode, or 640x200 and two colors in

graphics mode. Unfortunately, there were often problems with programs

not working properly with an EGA card since the EGA standard was not

fully backwards-compatible with CGA and MDA. EGA also used a nine-pin

adapter, but also had a distinct DIP switch visible from the outside.

PGA

The Professional Graphics Adapter (PGA) card was part of a

package developed by IBM. Costing over $4000 and taking three ISA Slots

when fully configured, this system offered 3-D rotation and 60

frame/second animation. It was aimed at the engineering and scientificcommunities, but was dropped by IBM with the introduction of VGA

1987.

VGA

With the introduction of these PS/2, IBM also introduced

the Video Graphics Array (VGA) standard. This new standard

offered 16 colors at a resolution of 640x480 pixels. One of the ways

that VGA was able to offer more colors was by using an analog

video signal is either all on or all off. By using an analog signal, the

VGA standard is able to provide 64 distinct levels for each color,

providing 643 or 262, 144 possible colors, although only 16 or 256



P a g e | 50

Figure 3.1.1

ATI AGP Video Card 128MB

PCI Express

PCI Express (Peripheral Component Interconnect Express),

officially abbreviated as PCIe, is a computer expansion card standard

designed to replace the older PCI, PCI-X, and AGP bus standards. PCIe has

numerous improvements over the aforementioned bus standards,

including higher maximum system bus throughput, lower I/O pin count

and smaller physical footprint, better performance-scaling for bus

devices, a more detailed error detection and reporting mechanism, and

native hot plugging. More recent revisions of the PCIe standard support

hardware I/O virtualization. See improvement of game graphic in Figure

3.0 on page 36.

The PCIe electrical interface is also used in a variety of other

standards, most notably ExpressCard, a laptop expansion card interface.

An I/O interconnect bus standard (which includes a protocol and

a layered architecture) that expands on and doubles the data transfer

rates of original PCI. PCI Express is a two-way, serial connection that

carries data in packets along two pairs of point-to-point data lanes,



P a g e | 51

compared to the single parallel data bus of traditional PCI that routes

data at a set rate. Initial bit rates for PCI Express reach 2.5Gb/s per lane

direction, which equate to data transfer rates of approximately 200MB/s.PCI Express was developed so that high-speed interconnects such as

1394b, USB 2.0, InfiniBand and Gigabit Ethernet would have an I/O

architecture suitable for their transfer high speeds.

PCI Express, also known as 3GIO (for third-generation Input/Output) is

compatible with existing PCI systems. See (Figure 3.1.2).



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Figure 3.1.2

MOTHERBOARDMotherboard is like a car chassis. In a car, everything is

connected to the chassis either directly or indirectly. In a PC, everything is

connected to the motherboard, either directly or indirectly. A

motherboard is a thin flat piece of circuit board, usually of green or gold,

usually slightly larger than a piece of paper. (See figure 3.2)A motherboard has a number of special sockets that accept

various PC components. There are sockets for the microprocessors (See

Figure 3.3), sockets for RAM (See Figure 3.4), sockets to provide power

(See Figure 3.5), connectors for floppy drives and hard drives (See Figure

3.6), and connectors for external devices such as mice, printer, joysticks,

and keyboard (See Figure 3.7). A few components are soldered directly to

the motherboard (See Figure 3.8). Between the various devices, themotherboard is filled with tiny wires called “traces,” which electrically link

the various components of the PC together (See Figure 3.9).

All motherboards also have multipurpose expansion slots that

allow the addition of optional components. There are thousands of

different types of optional devices that can be added to a PC, including



P a g e | 53

scanners, modems, network cards, sound cards, and tape backups. The

expansion slots allow optional devices to communicate with the PC. The

device that connects to the expansion slot is generically called anexpansion card or just a card. There are different types of expansion slots

for different types of cards (See Figure 4.0).

Motherboard Socket 478 PIV

Photo of a motherboard

Socket for a CPU

Figure 3.3



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Sockets for RAM

Figure 3.4



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24-pin ATX PS 12-pin AT PS

Socket for power plugs

Figure 3.5

Floppy and Hard Drive Connectors

Figure 3.6



P a g e | 57

Expansion slots – one slot has a card insertedFigure 4.0

The position of the expansion slots and external components is

very standardized. They have to be. The motherboard is mounted

to the box or case, the part of the PC that you actually see (Figure

4.1). The box needs to have holes that allow devices to access the

external connectors.



P a g e | 58

Motherboard in casing

Figure 4.1

Types of the Motherboard

A motherboard form factor just describes the dimensions or size

of the motherboard and what the layout of the motherboard components

are. It is important to understand the different motherboard form factors,

because you cannot take any motherboard and place it in a computercase. You must put an ATX board in an ATX case. So before we go on the

next topic we should know the difference about other motherboard.



P a g e | 59

AT

The first type of motherboard that we want to talk about is the

full AT motherboard. The full AT motherboard is 12 inches wide and 11inches long. The full AT suffered from a problem with accessing some of

the items on the motherboard because the drive bays hung over the

motherboard. This situation made installation and troubleshooting of the

components on the motherboard very difficult. See (Figure A).

Another problem with the layout of the full AT board is that the

expansion cards, once inserted into the systems, would cover theprocessor. This situation led to cooling problems due to the fact that

ventilation was insufficient to keep the chip from overheating.

Baby AT

The baby AT system board form factor has been one of the most

popular motherboard types until recent years. The baby AT board is 8.5

inches wide and 10 inches long. This motherboard can be easilyrecognized because it usually has a DIN keyboard connector in the top-

right corner of the board. See (Figure B).

The baby AT board was about two-thirds the size of the full AT

board and incorporated a socket 7 ZIF slot for classic Pentium processors.

The baby AT board usually had a mixture of ISA/EISA and PCI slots located

on the system board and included a plug and play BIOS.

Take a minute to consider some of the key components on the

baby AT motherboard The socket 7 ZIF slot is usually situated at the

bottom of the motherboard where the processor is to be installed. Also

notice the SIMM and DIMM sockets on the right side of the motherboard,

which are used to house RAM memory. To the left of the SIMM and

DIMM slots, are the primary and secondary EIDE controllers for

connecting the hard drives to the board. To the left of the EIDEcontrollers, notice the types of expansion slots that are used: There are

four PCI slots and three EISA slots. Above the PCI slots, there is a silver

circle, which is the CMOS battery.



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AT Motherboard

Figure A

Baby AT Motherboard

Figure B



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The Back Panel

The Unit Backplane

Figure 4.2

For example, if the motherboard has a connector for a keyboard,

there needs to be a hole in the box though which the keyboard plugs can

be inserted. (See Figure 4.2.1)

Equally important, if the expansion slots allow you to add cards

to the PC, then there must also be holes that allow different devices toconnect to their cards (See Figure 4.2.2 Highlight). Clearly, there must be

a certain type of box to go with a certain type, or layout, of motherboard.

Fortunately, there are very few different layouts of motherboard,

requiring only a few different types of boxes. We’ll visit this in more detail

later.

PS2 Keyboard and Mouse Inserted card from the back

Figure 4.2.1 Figure 4.2.2

We have here diagram about the parts of the motherboard (See

Figure 4.5.1) and also the backplane part (See Figure 4.5.2).



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Motherboard PartsFigure 4.5.1

Backplane Motherboard Part

Figure 4.5.1



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4.6.1

Active HeatSink

Figure 4.6.2

A component designed to lower the temperature of an electronic

device by dissipating heat into the surrounding air. All modern CPUs

require a heat sink. Some also require a fan. A heat sink without a fan is

called a passive heat sink; a heat sink with a fan is called an active heat



P a g e | 68

sink. Heat sinks are generally made of an aluminum alloy and often have

fins.

Passive HeatSink

Figure 4.6.3



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Active HeatSink

Figure 4.6.4

Memory Slots / Memory Banks

Memory slots also call memory banks are for Random Access

Memory modules (RAM). Each memory bank can receives a RAM module

designed for a specific PC motherboard (See Figure 4.7). Ranging from 2

to 4 banks, you will encounter single and dual-channel technologies.

With single-channel, you can use 1, 2, 3 or 4 Ram modules, and it

should work perfectly. On the other hand, with dual-channel technology,

if you fill only 1 bank, you will lose some strength from your module.

To get the most of it, you need to fill banks with the samemodule types, from the same manufacturer with exactly the same

memory amounts.

If you want 1GB of memory, you need to use 1G or if you have

two 512MB modules from the same manufacturer with the same



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technology type. This way, motherboards use the modules strength to its

full capacity. Otherwise it may not work at all.

Like the socket, to find out the type, the manufacturer and thetotal MB or GB quantity you can use, take a look in your motherboard's

book. You should be able to find everything you need. If you have 4

banks like Figure 4.7 below and fill all of it, you can power up your pc and

use it for multi-tasking. In your previous lesson on memory you’ll see the

difference between this two photo ddr3 and sdram. Specifically they

don’t have the same notch, that’s why you should not buy a new memory

and use it from the old one that would be incompatibility.

Memory Bank DDR 3 Memory Bank SDRAM

Figure 4.7

Main Power Connector

The main power connector is uses to get the electric energy from

the power supply which the motherboard requires to function properly.

24 Pins Main Power Connector

There are 2 main ATX power connector types for those

motherboard parts. The 20 pins + 4 pins (2 separate connectors on thesame motherboard), and the 24 pins. (See Figure 4.8). Not all power

supplies have the 2 types, but it is possible to work around the problem if

you run into an incompatibility situation. Which will be discussed in a

future power supply guide about how to install it and where to plug the

connectors.



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Figure 6.8.0

The ATX Power Supply

Does 300 Watt Power Supplies Give

Enough Power Or Should You Go With 400 Watt

Power Supplies Or Even Higher?

This is the kind of question that comes

up all the time. Peoples tend to not understand

how computer power supplies work. To find out,

you need to understand how the energy is

distributed throughout the hardware.

The hardware inside your computer

case requires a certain amount of power. It is

ranging from 4W to around 80W for a single

piece. If you have 200W as requirement then a

300 Watt power supply is enough.



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ATX Power Supply 24 Pin

Power Supply Connectors, Where to Plug Them?

Main power connectors are plugged to the motherboard. The

connector with 20 pins may be used on ATX motherboards and the

connector with 4 pins is used for extra power for CPUs and graphic cards.

Not all motherboards require the use of connector with 4 pins, if it's the

case; do not bother, you do not need to use all connectors anyway.

The Power Supply Connector

Figure 4.9

The CPU Fan or Fan connector is used for plugging the back/frontwall or side panel case fans or through the motherboard. As fans do not

require a lot of energy, the connector is small and very fragile, be careful

when working with them.



P a g e | 73

The Serial ATA and Molex connector is used for hard disk drives.

Having that connector on your power supply is a good thing as this

technology speed up drives data transfer.The Molex or peripheral connector with 4 pins is used for optic

drives as hard drives. It was the only connector for mass storage devices

before the SATA.

The FDD, small connector with 4 pins is used for floppy drives.

Here too, I recommend caution when working with small connectors like

this.

Fast and Easy Way to Identify the Best Power Supply Unit

A nice little tip you can use to figure out if a power supply is good

or not, is to put the unit in your hand and to feel its weight. Light power

supplies mean they have few components inside, and that is no good.

Today's computers require more and more powers. If your power supply

does not have the required components to meet today's computers, yourcomputer parts may die faster.

Heavier power supplies have more components than lighter one,

so better suited for today's computers. Of course there is more than this

to know about good power supplies, but without any knowledge this is

the best tip I can give you. Some of the incompatibility will be discussed

later on the next Power Supply topic.

Power Supply Connector Pin

Figure 5.0



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Types of Chipset

Northbridge

The northbridge typically handles communications among the

CPU, in some cases RAM, and PCI Express (or AGP) video cards, and the

southbridge.[2][3] Some northbridges also contain integrated video

controllers, also known as a Graphics and Memory Controller Hub

(GMCH) in Intel systems. Because different processors and RAM require

different signaling, a northbridge will typically work with only one or two

classes of CPUs and generally only one type of RAM.

Southbridge

The southbridge is one of the two chips in the core logic chipset

on a personal computer (PC) motherboard, the other being the

northbridge. The southbridge typically implements the "slower"

capabilities of the motherboard in a northbridge/southbridge chipset

computer architecture. In Intel chipset systems the southbridge is named

Input/Output Controller Hub (ICH).

The southbridge can usually be distinguished from the

northbridge by not being directly connected to the CPU. Rather, the

northbridge ties the southbridge to the CPU. Through the use of

controller integrated channel circuitry, the northbridge can directly link

signals from the I/O units to the CPU for data control and access.



P a g e | 75



P a g e | 76

The Northbridge Components

CPU

Principal component of a digital computer, composed of a

control unit, an instruction-decoding unit, and an arithmetic-logic unit.

The CPU is linked to main memory, peripheral equipment (including

input/output devices), and storage units. The control unit integrates

computer operations. It selects instructions from the main memory in

proper sequence and sends them to the instruction-decoding unit, which

interprets them so as to activate functions of the system at appropriate

moments. Input data are transferred via the main memory to the

arithmetic-logic unit for processing (i.e., addition, subtraction,

multiplication, division, and certain logic operations). Larger computers

may have two or more CPUs, in which case they are simply called

"processors" because each is no longer a "central" unit.

RAM

Computer main memory in which specific contents can be

accessed (read or written) directly by the CPU in a very short time

regardless of the sequence (and hence location) in which they were

recorded. Two types of memory are possible with random-access circuits,

static RAM (SRAM) and dynamic RAM (DRAM). A single memory chip is

made up of several million memory cells. In a SRAM chip, each memory

cell stores a binary digit (1 or 0) for as long as power is supplied. In a

DRAM chip, the charge on individual memory cells must be refreshed

periodically in order to retain data. Because it has fewer components,

DRAM requires less chip area than SRAM; hence a DRAM chip can hold

more memory, though its access time is slower.

Graphic Cards

PCI-E

A high-speed peripheral interconnect from Intel introduced in

2002. Note that although sometimes abbreviated "PCX," PCI Express is



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not the same as "PCI-X" (see PCI-SIG and PCI-X for comparison). As a

result of the confusion, "PCI-E" or "PCIe" is the accepted abbreviation.

Initially used for high-speed display adapters, and intending toeventually replace the PCI and AGP buses entirely, PCI Express was

designed to match the higher speeds of today's CPUs. It can

accommodate Gigabit and 10 Gigabit Ethernet and even support chip-to-

chip transfers.

AGPAccelerated Graphics Port) A high-speed 32-bit port from Intel

for attaching a display adapter to a PC. It provides a direct connection

between the card and memory, and only one AGP slot is on the

motherboard. AGP was introduced as a higher-speed alternative to PCI

display adapters, and it freed a PCI slot for another peripheral device. The

brown AGP slot is slightly shorter than the white PCI slot and is located

about an inch farther back. AGP was superseded by PCI Express.

The Southbridge Components (I/O Controllers)

Onboard Graphics Controller

This is usually called integrated graphics or on-board graphics,

and is low-performance and undesirable for those wishing to run 3D

applications. A dedicated graphics card on the other hand has its own

RAM and Processor specifically for processing video images, and thusoffloads this work from the CPU and system RAM. Almost all of these

motherboards allow the disabling of the integrated graphics chip in BIOS,

and have an AGP, PCI, or PCI Express slot for adding a higher-performance

graphics card in place of the integrated graphics.

IDE

(Integrated Drive Electronics) The standard hardware interface

for hard disks and optical discs in a computer. Introduced in 1986 with20MB of storage, capacities increased to 2TB by 2010. Years ago, IDE

drives replaced SCSI drives in high-end computers.

IDE is officially the AT Attachment (ATA) interface, and the "AT"

comes from the PC/AT, an early IBM PC that popularized the drives. The



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terms IDE, EIDE (Enhanced IDE), ATA and PATA (Parallel ATA) are

synonymous (see PATA and SATA). See IDE Connector (Figure 5.2).

Built-In Electronics

The controller electronics are built into the IDE drive,

requiring a simple circuit in the PC for connection. Two IDE

sockets are built onto the motherboard, each socket connecting

two drives via a 40-pin ribbon cable for optical discs and an 80-pin cable for hard disks (see below).

Master and Slave

IDE drives are configured as master and slave. Jumper

pins on the drive itself are used to set up the first drive on the

cable as master and the second one, if present, as a slave.

ATAPI

ATAPI is ATA for CD-ROM and DVD drives. The ATA

Packet Interface (ATAPI) was developed to allow CD-ROM drives

to run over the IDE interface by using commands similar to SCSI

drives.

SCSI

Small computer system interface, a parallel interface

standard used by Apple Macintosh computers, PCs, and many

UNIX systems for attaching peripheral devices to computers.

Nearly all Apple Macintosh computers, excluding only the

earliest Macs and the recent iMac, come with a SCSI port for

attaching devices such as disk drives and printers.

SCSI interfaces provide for faster data transmissionrates (up to 80 megabytes per second) than standard serial and

parallel ports. In addition, you can attach many devices to a

single SCSI port, so that SCSI is really an I/O bus rather than

simply an interface.



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Figure 5.2



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Ethernet

Ethernet is a family of frame-based computer networking

technologies for local area networks (LAN) See (Figure 5.4.1). It defines a

number of wiring and signaling standards for the Physical Layer of the

standard networking model as well as a common addressing format and a

variety of Medium Access Control procedures at the lower part of the

Data Link Layer.

Ethernet has been commercially available since around 1980,

largely replacing competing wired LAN standards. Most common are

Ethernet over twisted pair to connect end systems, and fiber optic

versions for site backbones. It is standardized as IEEE 802.3.

A standard 8P8C (often called RJ45) see (Figure 5.4.2) connector

used most commonly on cat 5 cables, a type of cabling used primarily in

Ethernet networks. If you don’t have a built-in Ethernet port you need a

LAN card.



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Ethernet Adapter or LAN Card RJ45 Ethernet

Cable

Build in LAN port

Figure 5.4.2

Sound Port

A sound port is a line-in port for listening to or recording from an

external device such as a digital audio player. If the source device doesnot have a line-out port to connect to the sound port, a stereo cable can

be run from the headphone jack on the source device to the line-in port

on the sound port. Software configurations may be required to hear the

device playing. If you don’t have any sound port or built-in sound (see

Figure 5.5) port on your motherboard, you need a Sound Card (see Figure

5.5.1).

Build in Sound Card

Figure 5.5



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Sound Card

Figure 5.5.1

CMOS Memory and BIOS

CMOS

Nonvolatile BIOS memory refers to a small memory on PC

motherboards that is used to store BIOS settings. It was traditionally

called CMOS RAM because it used a low-power Complementary metal-

oxide-semiconductor (CMOS) SRAM (such as the Motorola MC146818 or

similar) powered by a small battery when system power was off. The term

remains in wide use but it has grown into a misnomer: nonvolatile storage

in contemporary computers is often in EEPROM or flash memory (like the

BIOS code itself); the remaining usage for the battery is then to keep the

real-time clock going. See image BIOS and CMOS (Figure 5.6.1).

The typical NVRAM capacity is 512 bytes, which is generally

sufficient for all BIOS settings. The CMOS RAM and the real-time clock

have been integrated as a part of the southbridge chipset and it may not

be a standalone chip on modern motherboard.

BIOS CMOS CMOS BIOS

Figure 5.6.1

BIOS

The BIOS software is built into the PC, and is the first code run by

a PC when powered on ('boot firmware'). The primary function of the

BIOS is to load and start an operating system. When the PC starts up, the



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first job for the BIOS is to initialize and identify system devices such as the

video display card, keyboard and mouse, hard disk, CD/DVD drive and

other hardware. The BIOS then locates software held on a peripheraldevice (designated as a 'boot device'), such as a hard disk or a CD, and

loads and executes that software, giving it control of the PC. This process

is known as booting, or booting up, which is short for bootstrapping.

A BIOS will also have a user interface (or UI for short). Typically

this is a menu system accessed by pressing a certain key on the keyboard

when the PC starts. In the BIOS UI (See Figure 5.6.2), a user can:

Configure hardware

Set the system clock

Enable or disable system components

Select which devices are eligible to be a potential boot device

Set various password prompts, such as a password for securing

access to the BIOS UI functions itself and preventing malicious

users from booting the system from unauthorized peripheral

devices.

The BIOS provides a small library of basic input/output functions

used to operate and control the peripherals such as the keyboard, text

display functions and so forth, and these software library functions are

callable by external software. In the IBM PC and AT, certain peripheral

cards such as hard-drive controllers and video display adapters carried

their own BIOS extension ROM, which provided additional functionality.

Operating systems and executive software, designed to

supersede this basic firmware functionality, will provide replacement

software interfaces to applications.



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Figure 5.6.2

The INPUT / OUTPUT

Serial Port

In computing, a serial port is a serial communication physical

interface through which information transfers in or out one bit at a time

(contrast parallel port). Throughout most of the history of personal

computers, data transfer through serial ports connected the computer to

devices such as terminals and various peripherals. See (Figure 5.7.1)

While such interfaces as Ethernet, FireWire, and USB all send

data as a serial stream, the term "serial port" usually identifies hardware

more or less compliant to the RS-232 standard, intended to interface with

a modem or with a similar communication device.

Modern computers without serial ports may require serial-to-

USB converters to allow compatibility with RS 232 serial devices.



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Note:Not every computer will have the same number or type of ports. For

example, newer computers use USB ports for connecting a wide variety of

devices, from printers to digital cameras or a wireless mouse. Older computers

have fewer USB ports available, but newer ones are likely to offer 4 or 5.

Use this table in tandem with Figure 6.0 to locate device-to-PC

connector ports. Note that many devices use a USB connector these days;

so, for example, if you have a mouse with a USB connector, just plug it

into one of your USB ports.

Figure 6.0

Floppy Disk Drive and Connector

The floppy disk interface uses what is likely the strangest cable of all those in PCs today. It is similar to the standard IDE cable in that it is

usually a flat, gray ribbon cable. It is unusual in terms of the number of

connectors it has and how it is used to configure the setup of the floppy

disks in the system.

The floppy cable has 34 wires. There are normally five

connectors on the floppy interface cable, although sometimes there areonly three. These are grouped into three "sets"; a single connector plus

two pairs of two each (for a standard, five-connector cable) or three

single connectors. (See Figure 6.1.1)



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FDD Cable Set

Figure 6.1.1



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This type of expansion slot was specifically designed to deal with graphics

adapters. In fact, AGP stands for Accelerated Graphics Port. Older PCs

may sport this expansion slot, but the best video cards use PCI Express.

Type of Expansion Slot ISA/PCI/AGP

Figure 6.4

The Internal Computer Components

Motherboard

We Previous explain what is motherboard, the main circuit board of

your computer. If the CPU is the brains, then this is the heart.This is where you

will usually find your CPU and RAM clipped to, and the type of CPU and RAM you

can buy largely depends on the type of motherboard you have.

The motherboard can also be a deciding factor when buying a new

graphics card too.

CPU (Central Processing Unit)

We Previous explain what is CPU, this Is brains of the whole PC.

This is the section inside of your PC that does all the thinking, using

complex mathematical sums.This is the most important part of your



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computer set-up, and performs the majority of the complex tasks that

you tell your computer to do.

Measured in GHz, the higher the number, the more powerful andfaster your computer will be able to run.

Memory (RAM)

We Previous explain what is Random Access Memory, or RAM, is

memory that can be accessed in any order. The computer uses it for

short-term tasks while the computer is on, such as running programs.

Once the computer is turned off, nothing is saved.

RAM is usually considered to be the primary memory of the

computer, or primary storage. It is used to open and close applications,

and displaying and manipulating data.

Because the RAM is used regularly, some of the more expensive

RAM can have its own cooling system.

Modem

Usually hidden away inside the computer these days, the modem

allows you to access the internet.

A modem (also known by the more awkward name of

modulator/demodulator), connects to a phone line allowing the user to

access the internet.

Modems are becoming increasingly obsolete due to the more popular

router. See (Figure 6.5).



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In addition to supplying the computer's power needs, a desktop

computer's power supply also provides much-needed cooling with its

power supply fan. Some computers (such as servers, gaming systems andhigh-end PCs) have multiple power supplies with multiple fans. This

addresses two needs: the increased need for power due to high-speed or

high-workload components, and increased cooling capacity, since high-

speed and high-workload components generate a lot of heat.

A laptop power supply, however, is slightly different. The job of

converting electrical power from a wall socket into something a laptopcan use is divided between two components: the external power adapter

and the internal power supply. A laptop power adapter converts the

electricity from a wall outlet to something the internal power supply can

use. Typically this is a higher DC voltage than a desktop power supply

furnishes. The adapter converts the power you get at the wall outlet and

converts it to another voltage, often between 10 and 18 volts DC. From

there, the internal power supply further converts the voltage to suit theneeds of the computer.

AT Power Supply

There are two major types of computer power supplies: AT and ATX.

An AT power supply is what was used for most older computers.

This type of power supply powered the first personal computers made byIBM, and the standard was adopted for other manufacturers as well.

Specifically, it powered all AT and AT-compatible motherboards. The

connector of this power supply is Auxillary Port which is 6 pin and its has 2

port connector.

The AT-compatible motherboard obtained its power from a

special two-part power connector from the AT power supply. This power

connector contained four +5 volt DC wires, four ground (0 volt) wires, one- 5 volt wire, one +12 volt wire and one -12 volt wire. The remaining wire

was a signal wire that allowed the power supply to tell the motherboard

that "Power is good." With an AT power supply, you were required to

manually turn off your computer by pressing the power switch (which

generally was a dedicated On/Off switch).



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ATX Power Supply

With advances in software and operating systems, computers

could do more, such as enter "Power-Save" or "Sleep" mode. Software

could now be used to turn off the computer, rather than having to turn

off a computer with a power switch. This has all been made possible by

use of ATX power supplies and ATX-compatible motherboards. The ATX

power supply, therefore, is more complex.

An ATX power supply has more outputs that connect to an ATX-

compatible motherboard. Whereas the AT power supply only had 8

outputs, the ATX power supply uses either 20 or 24 outputs. Most ATX

power supplies take into account that an ATX motherboard can contain

either 20 or 24 outputs, so the extra 4 outputs are often split out as a

separate plug that will only fit one way into a 24 output motherboard

connector.

The ATX power supply also supports more voltage settings, and is

capable of accepting signals from the ATX-compatible motherboard other

than simply "Power Good." The 24-pin ATX power supply has the

following number of outputs, all voltages DC: three +3.3 volt, eight

ground (0 volt), five +5 volt, one -5 volt, two +12 volt, one -12 volt and

four "signal" wires ("Power Good," "+5 volt standby," "+3.3 volt sense"

and "Power on").

Warning:

AT and ATX power supplies are incompatible with each other's

motherboards. Trying to modify an ATX power supply to work with an AT-

compatible motherboard will be unsuccessful. The extra inputs on an ATX

power supply will not allow the power supply to function properly, since

there are more "signal" inputs on an ATX power supply than there are on

an AT motherboard.

Similarly, an ATX-compatible motherboard will not work with an AT power

supply because there are too few varieties of voltage available. All computer

processors that are Pentium MMX generation or newer use a primary (core)



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Types of Power Supply Label Connector

6.7

Hard Disk

If the CPU is the brain, then the Hard Disk is the long term

memory. Measured in Gigabytes (GB), the higher the GB the larger the

available memory.

With most computers, the hard disk is easily changed, but requires you to

open up your computer and can be quite daunting to the novice.

Hard disk drive Inner and outer layer

Figure 6.8

A Hard Disk Drive (HDD) is a non-volatile, random access device

for digital data. It features rotating rigid platters on a motor-driven

spindle within a protective enclosure. Data is magnetically read from and



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written to the platter by read/write heads that float on a film of air above

the platters.

Introduced by IBM in 1956, hard disk drives have fallen in cost

and physical size over the years while dramatically increasing in capacity.

Hard disk drives have been the dominant device for secondary storage of

data in general purpose computers since the early 1960s. They have

maintained this position because advances in their areal recording density

have kept pace with the requirements for secondary storage. Today's

HDDs operate on high-speed serial interfaces; i.e., serial ATA (SATA) orserial attached SCSI (SAS).

Serial Attached SCSI (SAS) is a computer bus used to move data

to and from computer storage devices such as hard drives and tape

drives. SAS depends on a point-to-point serial protocol that replaces the

parallel SCSI bus technology that first appeared in the mid 1980s in data

centers and workstations, and it uses the standard SCSI command set. SASoffers backwards-compatibility with second-generation SATA drives. SATA

3 Gbit/s drives may be connected to SAS backplanes, but SAS drives may

not be connected to SATA backplanes.



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SCSI Type Drive

Figure 6.8.1

SCSI Card

Figure 6.8.2



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Figure 6.8.3

Difference between IDE Cable (First Image) and Sata Cable(Second Image)

Motherboard

We already discuss what motherboard is. This is the main

circuit board of your computer. If the CPU is the brains, then this is

the heart.

This is where you will usually find your CPU and RAM

clipped to, and the type of CPU and RAM you can buy largelydepends on the type of motherboard you have.

The motherboard can also be a deciding factor when

buying a new graphics card too. See (Figure 6.9)



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(Figure 6.9)

Typical Motherboard Diagram



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These electronic components are held in place by soldered jointson the underside of the board. There are also other holes drilled into the

motherboard to accept spacers and screws for securing the motherboard

to the case. Most computer mainboards produced today are designed for

IBM-compatible PCs and currently account for approximately 90% of

global computer sales. The evolution of the mainboard has caused more

devices to be integrated into it. A typical PC has its processor main

memory and other important components connected to the mainboard.One very important component of the mainboard is the chipset that

supports the CPU. The chipset provides support between the CPU and the

various buses and external components. The chipset also controls the

features and capabilities of the motherboard.

Modern mainboards have these basic parts:

* Chipset that forms an interface between the processor's front-side

bus (FSB), main memory (RAM) and peripheral buses.

* Sockets(slots) into which one or more CPUs can be installed.

* Non-volatile memory chips that contain the system's BIOS.

* A clock generator that produces the system clock signal to

synchronize the different components.

* Expansion slots into which components such as video cards, sound

cards, NICs, etc. are installed.

* Power connectors that distribute power from the PSU to different

components such as CPU, chipset, memory (RAM) expansion cards, etc.

Above are listed the key components of a motherboard. There are others

that will follow.



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Expansion Slots:

Expansion slots enable the CPU to communicate with the peripheral

devices which expand the capability of the computer.

Different cards can be plugged into these slots to enhance the computer

such as video cards to improve graphics and sound cards to provide

better audio.

Battery:

This battery is referred to as CMOS battery and is responsible for keeping

the time and date. It usually has a life span of about 3 to 4 years.

Memory:

In a computer system, the CPU needs information and instructions to

perform properly. This information and instructions for the CPU are

stored in Random Access Memory (RAM). This memory is volatile and is

referred to as Primary Memory or Main Memory.

Ports:

Ports allow external devices to be connected to the computer

motherboard. There are different types of ports located on the

motherboard such as parallel, serial, universal serial bus (USB) and SCSI

(small computer system interface).

Until up to a few years ago, printers were connected to parallel ports but

now they are being replaced with the faster USB port. Low speedperipherals such as modems, mice and some scanners were connected to

the serial port but are now connected by USB.

USB 1.0 had a data transfer rate of approximately 12 Mbit/s. The upgrade

to USB 2.0 increased the data transfer rate by 40x to approximately 480

Mbit/s.

Now there is USB 3.0 which can transfer data faster and supply more

power while being backward compatible with USB 2.0. This USB 3.0

standard promises a theoretical super speed of 5 Gbit/s.

This port can connect up to 127 daisy-chained devices all at once.



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Power Connector:

Most new motherboards now come with a 24-pin connector. Older

motherboards with 20-pin connectors can still be used with a 24-pinpower supply since this 24-pin connector can be separated into 20-pin

and 4-pin connectors.

Integrated Graphics and Audio:

Today, most of the motherboards manufactured include integrated

graphics, audio and Gigabit LAN.

Hard Drive Data Transfer Modes-(Interface):

Motherboards are designed to provide different data transfer rates. Very

old computers used the UDMA/33 interface but this was increased to

UDMA/66 which doubled the data-transfer rate.

The data transfer rate of a hard drive is the time used to read/write

information. This interface mode was upgraded to UDMA/100 and then

finally to UDMA/133.

These characteristics apply to Parallel ATA hard drives. For a long time,

the UDMA/133 remained the fastest interface until the inception of the

Serial ATA (SATA Rev 1.0) drive which has a data transfer rate of 1.5

Gbit/s. These have now improved to SATA Rev. 2.0 with data transfer

rates of 3.0 Gbit/s.

These hard drives can be operated in different modes called RAID

(Redundant Array of Independent Disks). RAID requires more than one

hard drive.

This provides speed by writing/reading information to more than one

d i i lt l ll d ' t i i ' (RAID 0)

Computer Troubleshooting I Guidelines

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