chapter 2 motherboard

8/9/2019 Chapter 2 Motherboard

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Unit 2: Motherboard

Prepared by : Mohd Zuhaimi b Zolkifli

E5164 COMPUTER SYSTEM DIAGNOSIS AND MAINTENANCE


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Motherboard?

The Motherboard is the main chassis of

the PC.

All data that flows from component tocomponent inside the computer at some

point goes through the motherboard.

That is the Motherboards main function to

direct data flow to the right components.


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Function of motherboard maincomponents

BIOS & CMOS

Sockets

Ports

CPU

Expansion Slot

Buses

Chipset


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CPU?


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CPU Central Processing Unit

The brain of computer

The portion of a computer system that

carries out the instructions of a computer

program.

Does all the calculations and performs

90% of all the functions of a computer.


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Processor Socket/Slot (1)

Sockets are basically flat and have several rows

of holes arranged in a square.

Processor slot is another method of connectingprocessor on the motherboard but one which

an Intel Pentium II or Pentium III-class processor

on a special expansion card can be inserted.

More complex processor (Intel Itanium) use a

package known as a pin array cartridge (PAC).


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Processor Socket/Slot (2)

CPU SOCKET

SLOT 1 CONNECTOR

SLOT

PAC SOCKET


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Type of Expansion Slot (1)


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Type of Expansion Slot (2)


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Related Buses


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What is bus?The paths the computer usesThe paths the computer uses

to transport data from one component toto transport data from one component to

another.another. (It doesn't matter how fast your CPU is or your diskdrive if the bus isn't wide and fast.)

Fast and wide?TheThe widthwidth of the bus isof the bus is

determined by how many bits of data thedetermined by how many bits of data the

bus can transfer in one operation.bus can transfer in one operation.(Therefore, a

32-bit bus is wider than a 16-bit bus.)TheThe speedspeed of aof a

bus is rated in megahertz (MHz), which isbus is rated in megahertz (MHz), which isone million cycles per second.one million cycles per second. (A single hertz isone electronic cycle that performs one operation.)


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Difference between computer

buses

Data width

Cycle rate

To determine the bandwidth, or

the total amount of data that the

bus can transmit.

Device

Management

The maximum number of

supported devices and the

difficulty of configuring them.

TypeTwo types of buscommunications, serial and

parallel.


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Front Side Bus - FSB

The FSB is the interface between the CPU and themotherboard, specifically the North Bridge/MemoryController Hub.

Also connects the various hardware components tothe main microprocessor, or central processing unit(CPU).

The FSB is bi-directional, meaning data can flow both

ways, allowing components to send and receive datafrom the CPU.

Speed of FSB is depends on how wide the front sidebus is, its frequency, and the amount of data it can

process per clock tick of the CPU


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FSB - Example


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Memory Bus The memory bus is the interface between

the RAM and the motherboard

The memory bus is made up of two parts:the data bus and the address bus

Data Bus: which carries actual memory datawithin the PC

Address Bus: used to select the memoryaddress that the data will come from or go toon a read or write


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Input/Output Buses (1)

I/O buses connect the CPU to all othercomponents, except RAM.

On modern PCs, usually they are fourbuses: ISA bus, which is an old low speed bus, soon to be

excluded from the PC design.

PCI bus, which is a new high speed bus.

USB bus (Universal Serial Bus), which is a newlow speed bus. AGP bus, which solely is used for the graphics card.


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Input/Output Buses (2)


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Chipset


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Whats a chipset?A collection of chips orA collection of chips orcircuits that perform interface andcircuits that perform interface and

peripheral functions for the processorperipheral functions for the processor.

Collection?Usually the circuitry thatUsually the circuitry thatprovides interfaces for memory, expansionprovides interfaces for memory, expansion

cards, onboard peripherals and generallycards, onboard peripherals and generallydictates how a motherboard will talk to thedictates how a motherboard will talk to theinstalled peripherals.installed peripherals.

- Functions of chipset can be divided into- Functions of chipset can be divided intotwo major functional groups :two major functional groups : NorthbridgeNorthbridgeandandSouthbridgeSouthbridge..


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Northbridge

Management of high-speed peripheral

communications.

Responsible forcommunications with

integrated video using AGP and PCIe, and

processor-to-memory communications.


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Southbridge

Responsible forproviding supportto themyriad onboard peripheral (PS/2, Parallel,IDE etc), managing theircommunications

with the rest of the computerand theresource given to them.

Also responsible for managingcommunications with the other expansionbuses (PCI, USB and legacy buses).


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Basic Input/Output System (BIOS)

Chip

Special memory chip contains the BIOS software that

tells the processor how to interact with the rest of the

hardware in the computer.


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CMOS(1)

PC has to keep certain setting when its turned offsuch as:

Date

Time

Hard Drive Configuration

Memory

PC keeps these settings in a special memory chipcalled the Complimentary Metal Oxide

Semiconductor (CMOS) chip.


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CMOS(2)

To keep it setting, the memory must have

power constantly.

Motherboard manufacturers include a

small battery called CMOS Battery to

power the CMOS memory.


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Socket (1)

IDE Socket

Usually use to

connect hard

drive, CD-RW,DVD etc. JTAG IDE Socket

IDE Connector


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Socket (2)

SIMM Socket

holds a single

SIMM

SIMM (single in-

line memory

module )


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Socket (3)

DIMM Socket

Usually use for

DRAM, SDRAM,

non-standard DRAM

module etc

DIMM - Dual in-line

memory module,

comprises a series of

dynamic random

access memory

integrated circuits


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Socket (4)

FDD Socket

used for floppy disk

drives.


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Port (1)

USB Port

the easiest and

most common

technique forconnecting

hardware

simply plug thehardware into your

computer.


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Port (2)

iLink/IEEE1394/FireWire

the highest-

performance

hardware connection

used for digital video

cameras and

external hard disks Most new computers

include at least one

iLink port


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Port (3)

PC Card

to support extremely small accessories, such as wireless adapters


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Port (4)

PS/2

the standard

connection for your

keyboard andmouse.


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Port (5)

Serial or parallel

ports

the oldest

connection type forexternal hardware

accessories

are easy to connect software configures

these connections

automatically


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Main Memory


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Introduction

Also known as RAM(Random Access Memory)

Needs to have electrical power in order to

maintain its information (When power is lost, theinformation is lost too!)

It can be directly accessed by the CPU

Main memory is expensive compared to

external memory so it has limited capacity


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How it work?

A memory chip is an integrated circuit(IC) made of millions of transistors andcapacitors.

A transistor and a capacitor are paired tocreate a memory cell, which represents asingle bit of data. (in DRAM)

The capacitor holds the bit of information. The transistor acts as a switch that lets thecontrol circuitry on the memory chip readthe capacitor or change its state.

A capacitor is like a small bucket-


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pthat is able to store electrons.

To store a 1 in the memory cell,

the bucket is filled with electrons.To store a 0, it is emptied.

The problem with the capacitor'sbucket is that it has a leak.

The memory controllerhas tocome along and recharge all ofthe capacitors holding a 1 beforethey discharge.

The memory controller reads thememory and then writes it rightback.


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Memory Organisation

Magnetictapes

Magneticdisks

I/Oprocessor

CPU

Mainmemory

Cachememory

Auxiliary memory

Register

Cache

Main Memory

Magnetic Disk

Magnetic Tape


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Memory Signals


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NOTE

Each motherboard supports memory

based on the speed of the front side bus

(FSB) and the memorys form factor.

Example: if FSB rated at max speed

533MHz and memory rated at 300MHz,

the memory will operate at only 300Mhz.

(make the computer operate slower thanwhat it could)


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Memory Packaging

The memory slots on the motherboard are

designed for particular module form

factors or styles.

DIP, SIMM and SIPP are obsolete

memory packages.

The most popular form factors for primary

memory modules today are DIMM, RIMM,SoDIMM and MicroDIMM


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Memory Module SIMM (1)

Single in-line memory module containing random access memory used in

computers from the early 1980s to the late 1990s

DRAM technologies used in SIMMs include EDOand FPM.

The first variant of SIMMs has 30 pins and provides9 bits of data.

The second variant of SIMMs has 72 pins andprovides 32 bits of data (36 bits in parity versions)


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Memory Module SIMM (2)

30 pinsSize: 256 KB, 1 MB, 4 MB,

16 MB

Have 12 address lines,

which can provide a total of

24 address bits.

With an 8 bit data width, this

leads to an absolute

maximum capacity of 16

MiB.72 pinsStandard sizes: 1 MiB, 2 MiB, 4 MiB, 8 MiB, 16 MiB,

32 MiB, 64 MiB, 128 MiB

With 12 address lines, which can provide a total of

24 address bits, two ranks of chips, and 32 bit data

output, the absolute maximum capacity is 227 = 128

MiB.


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Memory Module DIMM (1)

Dual In-line Memory Module

comprises a series of dynamic random

access memory integrated circuits.

64-bit memory modules that are used as a

package for the SDRAM family (SDRAM,

DDR and DDR2.

DIMM differentiate the functionality of the

pins on one side of the module from the

corresponding pins on the other side.


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168-pin SDRAM module

184-pin DDR SDRAM module

DIMM slots


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DIMM range in capacity from 8 MB to 1

GB per module and can be installed singly

instead of in pairs.

Another standard, Rambus in-line

memory module (RIMM), is comparable

in size and pin configuration to DIMM but

uses a special memory bus to greatlyincrease speed.


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Memory Module SODIMM (1)

Many brands of notebook computers useproprietary memory modules, but severalmanufacturers use RAM based on the smalloutline dual in-line memory module

(SODIMM) configuration. SODIMM cards are small, about 2 x 1 inch (5 x

2.5 cm), and have 144 or 200 pins.

Capacity ranges from 16 MB to 1 GB permodule.

Sub-notebook computers use even smallerDIMMs, known as MicroDIMMs, which have

either 144 pins or 172 pins.


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Memory Module SODIMM (2)


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Type Of Memory (DRAM)

Dynamic random access memory

Has memory cells with a paired

transistor and capacitorrequiringconstant refreshing.


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Type Of Memory (SRAM)

Static random access memory

Uses multiple transistors, typically four to

six, for each memory cell but doesn't have

a capacitor in each cell. It is used primarily

for cache.


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Type Of Memory (FPM DRAM)

Fast page mode dynamic random

access memory

It waits through the entire process of

locating a bit of data by column and row.

Then reading the bit before it starts on the

next bit.

Maximum transfer rate to L2 cache is

approximately 176 MBps.


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Type Of Memory (VideoRAM)

A type of RAM used specifically for videoadapters or 3D accelerators.

VRAM normally has two independent accessports allowing the CPU and graphics processorto access the RAM simultaneously.

VRAM is located on the graphics card andcomes in a variety of formats.

The amount of VRAM is a determining factor inthe resolution and color depth of the display.

VRAM is also used to hold graphics-specificinformation such as 3-D geometry data and

texture maps.


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Type Of Memory (EDO DRAM)

Extended data-out dynamic randomaccess memory

Does not wait for all of the processing of

the first bit before continuing to the nextone.

As soon as the address of the first bit is

located, EDO DRAM begins looking forthe next bit.

It is about five percent faster than FPM.Maximum transfer rate to L2 cache is



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Type Of Memory (SDRAM)

Synchronous dynamic random accessmemory

Takes advantage of the burst mode concept togreatly improve performance.

It does this by staying on the row containing therequested bit and moving rapidly through thecolumns, reading each bit as it goes.

The idea is that most of the time the data

needed by the CPU will be in sequence. SDRAM is about five percent faster than EDO

RAM and is the most common form in desktopstoday. Maximum transfer rate to L2 cache is



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Memory bank system

H l d t


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How memory load onto

motherboard


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Operating System and Boot

Processes


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Introduction

OS provides aconsistentenvironment forother software toexecute commands.

Gives users aninterface with thecomputer so theycan send commands(input) and receivefeedback or result(output)

OS

Processor

Devices

Hard disks Memory

Input/Output


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OS Terms and Concept

Version normally described by anumber, which tells you how new theproduct is in relation to other versions ofthe product.

Source actual code that defines how apiece of software work. (open source:can modify/ close source: can't modify)

Shell a program that runs on top of theOS and allows the user to issuecommands through a set of menus orsome other graphical interface.

Graphical User Interface (GUI) a method


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Graphical User Interface (GUI) a method

by which a person communicates with a

computer. Network any group of computer that have a

communication link between them.

Cooperative Multitasking a multitaskingmethod that depends on the application itself

to be responsible for using and then freeing

access to the processor.


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Preemptive Multitasking a multitasking

method in which OS allots each

application a certain amount of processortime and then forcibly takes back control

and gives another application or task

access to the processor. Multithreading ability of a single

application to have multiple requests in to

the processor at one time.


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Microsoft Windows

Microsoft Windows was born out of the

Microsoft Disk Operating Systems (MS-

DOS)

The limitations of the DOS command-lineinterface became apparent.

Solution make the OS easier to

navigate, more uniform, and user friendly.

1985 1st version of Windows was

released.

Wi d 1


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Windows 1


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Window 1 - 1985

Featured the tiling window, mouse

support, and menu systems.

Also offered cooperative multitasking,

meaning that more than one Windowsapplication could run concurrently.

It didnt use icons.

More graphical version of the

DOSSHELL.exe program.


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Windows 2


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Windows 2.0 - 1987

Added icons and allowed application

windows to overlap each other, as well as

tile.

Support was also added for PIFs (programinformation files), which allowed the user

to configures Windows to run their DOS

applications more efficiently.

Wi d 3


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Windows 3.x


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Windows 3.x 1990an

A far more flexible memory model (morethan 640kb normally imposed by DOS)

The addition of the File Manager and

Program Manager

Allowed for network support.

Could operate in 386 Enhanced mode

(used part of the hard drive as virtual memory able to use disk memory to supplement the RAM

in the machine.)

Version 3 1(1992) provide better


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Version 3.1(1992) provide better

graphical display capability and multimedia

support, improved Windows error-protection system and let application work

together easily (object linking and embedding OLE)

Version 3.11 (Windows for Workgroup) support both 16-bit and 32-bit application.


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Windows 95


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Windows 95 - 1995

Integrated the OS and the shell.

Designed to be hybrid of the features of

previous DOS versions and newer 32-bit

systems.

Support both 32-bit and 16-bit driver as

well as DOS driver.

Support for Plug and Play (PnP) standard.


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Windows 98/Me/NT/2000/XP


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Other OS

Windows Server 2003 Windows Vista

MAC OS

Linux


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Supplying Power

The internal power supply turns on andinitializes.

The power supply takes some time until it can

generate reliable power for the rest of thecomputer, and having it turn on prematurelycould potentially lead to damage.

Therefore, the chipset will generate a reset

signal to the processor until it receives thePower Good signal from the power supply.


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Bootstrap

A technique which a simple computer programactivates a more complicated system of

programs.

Example: In the start up process of a computersystem, a small program such as BIOS,

initializes and tests that hardware, peripherals

and external memory devices are connected,

then loads a program from one of them andpasses control to it, thus allowing the loading of

larger programs, such as an operating system.


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Power-on self-test (POST)

It is the first step of the more general

process called initial program load (IPL),

booting, or bootstrapping.

On power up, the main duties of POSTare handled by the BIOS, which may hand

some of these duties to other programs

designed to initialize very specificperipheral devices, notably for video and

SCSI initialization.

Principal duties of the main BIOS


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Principal duties of the main BIOS

during POST

Verify the integrity of the BIOS code itself Find, size, and verify system main memory

Discover, initialize, and catalog all system busesand devices

Pass control to other specialized BIOSes (if andwhen required)

Provide a user interface for system'sconfiguration

Identify, organize, and select which devices areavailable for booting

Construct whatever system environment that isrequired by the target OS


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1st stage of typical POST

2nd stage of a POST

Boot Process of DOS Operating


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Boot Process of DOS Operating

System

1. Once the computer system is turned on,the BIOS performs a series of activitiescalled POST that checks to see whether

the peripherals in the system are inperfect order.

2. This Pre Boot Sequence consists of a

series of steps that starts with theexecution of software stored in the ROMcalled firmware.


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5 If the bootable disk is not the floppy the


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5. If the bootable disk is not the floppy, the

MBR finds and searches the partition

table to load and scan all the extendedpartitions to find the primary partition.

6. When it finds one, it implies that it is the

bootable partition, and, the OperatingSystem loader (bootstrap loader) is

loaded from that partition onto the

memory.7. A boot strap loader is a special program

that is present in the boot sector of the

bootable drive

8. MS DOS Operating system comprises of the following files: ---


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IO.SysMSDOS.SysCommand.Com

Config.SysAutoexec.bat

Mandatory

Should be present in the

bootable drive

If not found, then the

message,"Non-system

disk or disk error -Replace and press any

key when ready"

Optional

9. The boot strap loader first loads the IO.Sys file.(responsible for Input Output in the DOS


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(responsible for Input Output in the DOSenvironment.)

10.The next file that is loaded is the MSDOS.syswhich is the core of the DOS operating system.(responsible for Memory management andProcessor Management in the DOS environment.)

11.The MSDOS.Sys file now searches to find the

name of the command interpreter in theConfig.Sys file and when it finds one, it loads thesame onto the memory.

12.If no command interpreter is specified in theConfig.Sys file, the Command.Com file is loadedas it is the default command interpreter of DOSOperating system.

13.You can load a different command interpreter byspecifying the following in the Config.Sys file.

14.The last file to be loaded and executed is


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14.The last file to be loaded and executed is

the Autoexec.bat file that contains a

sequence of DOS commands.15.Now, the prompt is displayed and you

can see the drive letter of the bootable

drive displayed on your screen indicative

of the fact that the Operating System has

been loaded successfully from that drive.

B t Di


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Boot Disc

What?

A boot disk will allow you to boot off of a

diskette instead of your hard drive. Thisdiskette can be used to fix issues that may

arise during the lifetime of your computer.

C ti Wi d XP b t di k


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Creating a Window XP boot disk

The Microsoft Windows XP CD is abootable CD and in many cases you

should not need a bootable floppy

diskette. Booting from the Windows XPCD will allow you to not only install/re-

install Windows XP but will also allow you

to troubleshoot it.

I t t fil i B t Di


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Important file in Boot Disc

Boot.ini - which contains configurationoptions for a boot menu.

NTLDR - which contains the main Boot

loader itself

Ntdetect.com - To load an NT-based OS

(NTLDR is actually required. If boot.ini is missing, NTLDRwill default to \Windows on the first partition of the first harddrive. Many desktops in the home are in this configurationand a missing boot.ini file will simply generate an error

stating it is missing, then boot into Windows successfully.)

Create MS-DOS bootable


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diskette

When formatting a floppy diskette, users have theoption of creating a MS-DOS startup disk,

follow the below steps to do this.

1. Place diskette in the computer.2. Open My Computer, right-click the A: drive and

click Format.

3. In the Format window, check Create an MS-

DOS startup disk.

4. Click Start

How to use a boot diskette


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How to use a boot diskette

1. Place the diskette into write-protect mode (in case avirus is on the computer, this will not allow the virusto transfer itself onto the diskette).

2. Insert the diskette into the computer and reset or

turn on the computer to begin the boot process.3. As the computer is booting, answer the questions

prompted (if any).

4. Once at the A:\> take the appropriate actions

depending upon the situation of the computer.


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Resources System

Interrupt Request (IRQ)

DMA Channel

I/O Addresses

Interrupt Requests (IRQ)


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Interrupt Requests (IRQ)

What? IRQ manage various hardwareoperations. Devices such as sound cards,modems, and keyboards can all sendinterrupt requests to the processor.

Example: when the modem needs to run aprocess, it sends an interrupt request tothe CPU saying, "Hey, hold up, let me do

my thing!" The CPU then interrupts itscurrent job to let the modem run itsprocess.

IRQ (2)


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Q ( ) It is important to assign different IRQ addresses to

different hardware devices - the interrupt requestsignals run along single IRQ lines to a controller.

This interrupt controller assigns priorities to incomingIRQs and sends them to the CPU.

Since the interrupt controller can control only onedevice per IRQ line, if you assign the same IRQaddress to multiple devices, you are likely to get anIRQ conflict. This can cause a range of errors from not

allowing network connections to crashing yourcomputer.

So make sure you assign unique IRQs to newhardware you install and avoid the frustration and

keyboard throwing that conflicts can cause.

Direct Memory Access (DMA)


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Direct Memory Access (DMA)

Method of transferring data from the computer'sRAM to another part of the computer without

processing it using the CPU.

While most data that is input or output from yourcomputer is processed by the CPU, some data

does not require processing, or can be processed

by another device.

In these situations, DMA can save processingtime and is a more efficient way to move data from

the computer's memory to other devices.

DMA (2)


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DMA (2)

For example, a sound card may need toaccess data stored in the computer'sRAM, but since it can process the dataitself, it may use DMA to bypass the CPU

In order for devices to use direct memoryaccess, they must be assigned to a DMAchannel. Each type of port on a computer

has a set of DMA channels that can beassigned to each connected device.

I/O Addresses


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I/O Addresses

Resources used by virtually every devicein the computer.

Conceptually; they represent locations in

memory that are designated for use byvarious devices to exchange information

between themselves and the rest of the

PC.

I/O Addresses Spaces


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I/O Addresses Spaces

Unlike IRQ and DMA channels, which areof uniform size and normally assigned one

per device, some devices use more than

one because many devices wrapped intoone package such as sound card.

I/O addresses vary in size - some devices

have much more information to movearound than others


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Motherboard Fault Symptoms

Basic Troubleshooting Method


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Basic Troubleshooting Method

chapter 2 motherboard

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