Unit 2 Motherboard

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Unit 2: Motherboard

Prepared by : Mohd Zuhaimi b Zolkifli

E5164 ± COMPUTER SYSTEM DIAGNOSIS AND MAINTENANCE



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.





Function of motherboard main

components

BIOS & CMOS

Sockets

Ports

CPU

Expansion Slot

Buses

Chipset



CPU?



CPU ± Central Processing Unit

The µbrain¶ 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.



Processor Socket/Slot (1)

Sockets are basically flat and have several rows

of holes arranged in a square.

Processor slot is another method of connecting

processor 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).





Type of Expansion Slot (1)



Type of Expansion Slot (2)



Related Buses





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 bus

communications, serial and

parallel.



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 canprocess per clock tick of the CPU



FSB - Example



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



Input/Output Buses (1)

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

On modern PCs, usually they are four

buses: ± 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 (Univ ersal Ser i al Bus), which is a new low speed bus.

± AGP bus, which solely is used for the graphics card.



Input/Output Buses (2)



Chipset



What¶s a chipset? A collection of chips or A collection of chips or circuits that perform interface and circuits that perform interface and

peripheral functions for the processor peripheral functions for the processor .

Collection? U sually the circuitry that U sually the circuitry that provides interfaces for memory, expansion provides interfaces for memory, expansion

cards, onboard peripherals and generally cards, onboard peripherals and generally dictates how a motherboard will talk to thedictates how a motherboard will talk to theinstalled peripherals.installed peripherals.

-- Functions of chipset can be divided intoFunctions of chipset can be divided intotwo major functional groups :two major functional groups : NorthbridgeNorthbridgeand and SouthbridgeSouthbridge..



Northbridge

Management of high-speed peripheral

communications.

Responsible for communications with

integrated video using AGP and PCIe, and

processor-to-memory communications .



Southbridge

Responsible for providing support to themyriad onboard peripheral (PS/2, Parallel,IDE etc), managing their communications

with the rest of the computer and theresource given to them.

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





CMOS(1)

PC has to keep certain setting when it¶sturned off such as:

± Date

± Time

± Hard Drive Configuration

± Memory

PC keeps these settings in a specialmemory chip called the ComplimentaryMetal Oxide Semiconductor (CMOS) chip.



CMOS(2)

To keep it setting, the memory must have

power constantly.

Motherboard manufacturers include asmall battery called CMOS Battery to

power the CMOS memory.



Socket (1)

IDE Socket

± Usually use to

connect hard

drive, CD-RW,

DVD etc. JTAG IDE Socket

IDE Connector



Socket (2)

SIMM Socket

± holds a single

SIMM

± SIMM (single in-

line memory

module )



Socket (3)

DIMM Socket

± Usually use for

DRAM, SDRAM,

non-standard DRAMmodule etc

± DIMM - Dual in-line

memory module,

comprises a series of

dynamic random

access memory

integrated circuits



Socket (4)

FDD Socket

± used for floppy disk

drives.



Port (1)

USB Port

± the easiest and

most common

technique for

connecting

hardware

± simply plug thehardware into your

computer.



Port (2)

iLink/IEEE 1394/FireWire

± the highest-

performancehardware connection

± used for digital video

cameras and

external hard disks ± Most new computers

include at least one

iLink port



Port (3)

PC Card

± to support extremely small accessories, such

as wireless adapters



Port (4)

PS /2

± the standard

connection for your

keyboard and

mouse.



Port (5)

Serial or parallel

ports

± the oldest

connection type for

external hardware

accessories

± are easy to connect ± software configures

these connections

automatically



Main Memory



Introduction

Also known as RAM ( Random Access Memory)

Needs to have electrical power in order to

maintain its information (W hen 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



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 the

control circuitry on the memory chip readthe capacitor or change its state.





Memory Organisation

Magnetictapes

Magneticdisks

I /Oprocessor

CPU

Mainmemory

Cachememory

Auxiliary memory

Register

Cache

Main Memory

Magnetic Disk

Magnetic Tape







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



Memory Module ± SIMM (1)

Single in-line memory module

containing random access memory used incomputers from the early 1980s to the late 1990s

DRAM technologies used in SIMMs include EDOand FPM.

The first variant of SIMMs has 30 pins andprovides 9 bits of data.

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





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.




168-pin SDRAM module

184-pin DDR SDRAM module

DIMM slots




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.



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 x2.5 cm), and have 144 or 200 pins.

Capacity ranges from 16 MB to 1 GB per module.

Sub-notebook computers use even smaller DIMMs, known as MicroDIMMs, which haveeither 144 pins or 172 pins.



Memory Module ± SODIMM (2)



Type Of Memory (DRAM)

Dynamic random access memory

Has memory cells with a paired

transistor and capacitor requiringconstant refreshing.



Type Of Memory (SRAM)

Static random access memory

Uses multiple transistors, typically four to

six, for each memory cell but doesn't havea capacitor in each cell. It is used primarily

for cache.



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.



Type Of Memory (VideoRAM)

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

VRAM normally has two independent access

ports allowing the CPU and graphics processor to 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.



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 for thenext bit.

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




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




Memory bank system



How memory load onto

motherboard



Operating System and Boot

Processes



Introduction

OS ± provides aconsistentenvironment for other software to

execute commands. Gives users an

interface with thecomputer so theycan send commands(input) and receivefeedback or result(output)

OS

Processor

Devices

Hard disks Memory

Input/Output



OS Terms and Concept

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

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

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



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.



Preemptive Multitasking ± a multitasking

method in which OS allots each

application a certain amount of processor time 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.











Windows 2.0 - 1987

Added icons and allowed application

windows to overlap each other, as well as

tile.

Support was also added for PIFs (program

information files), which allowed the user

to configures Windows to run their DOS

applications more efficiently.



Windows 3.x



Windows 3.x ± 1990an

A far more flexible memory model ( more

than 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.)





Windows 95





Windows 98/Me/NT/2000/XP

Wi d 98/M /NT/2000/XP



Windows 98/Me/NT/2000/XP

Windows 98/Me released after 95. Then Windows NT ± designed to be far more

powerful, uses an architecture based entirelyon 32-bit code and is capable of accessing upto 4GB of RAM.

Then Windows 2000 ± used the sameinterface as Windows 98 with a few important

enhancement. Windows XP ± come in 3 version (X P Home,

X P Professional and Media Center), containsmore corporate and network features.





Boot Process

Supplying Power

Bootstrap

Core Test POST

OS Search

Loading OS



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 the computer, and having it turn onprematurely could potentially lead todamage.

Therefore, the chipset will generate a resetsignal to the processor until it receives thePower Good signal from the power supply.





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 POST

are 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.

P i i l d ti f th i BIOS



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



POST beeps code

Beeps Meaning

Steady, short beeps Power supply may be bad

Long continuousbeeps

Memory failure

Steady, long beeps Power supply bad

No Beeps Power supply bad, system not plugged in, or power not turned on

One long, two short

beeps

Video card failure



1st stage of typical POST

2nd stage of a POST

Boot Process of DOS Operating



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.



3. After the BIOS is done with the pre boot

activities, it searches for the Master BootRecord in the first physical sector of the

bootable disk.

4. Note that a floppy disk cannot be

partitioned and hence does not contain

the MBR . Hence, if the bootable disk is

floppy, this process is skipped and the

boot strap loader is loaded in thememory.



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

MBR finds and searches the partition

table to load and scan all the extended

partitions 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



8. MS DOS Operating system comprises

of the following files: ---

IO.Sys

MSDOS.Sys

Command.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.



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

10.The next file that is loaded is the MSDOS.syswhich is the core of the DOS operating system.( responsible for Memory management and Processor 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 the

Config.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 Th l t fil t b l d d d t d i



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 indicativeof the fact that the Operating System has

been loaded successfully from that drive.



Boot Disc

What?

± A boot disk will allow you to boot off of a

diskette instead of your hard drive. This

diskette can be used to fix issues that may

arise during the lifetime of your computer.



Creating a Window XP boot disk

The Microsoft Windows XP CD is a

bootable 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.



Important file in Boot Disc

Boot.ini - which contains configuration

options 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



Create MS-DOS bootable

diskette

When formatting a floppy diskette, users have the

option 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

1. Place the diskette into write-protect mode (incase a virus is on the computer, this will notallow the virus to transfer itself onto thediskette).

2. Insert the diskette into the computer and resetor turn on the computer to begin the bootprocess.

3. As the computer is booting, answer thequestions prompted (if any).

4. Once at the A:\> take the appropriate actionsdepending upon the situation of the computer.



Resources System

Interrupt Request (IRQ)

DMA Channel

I/O Addresses



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)



IRQ (2) 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 your computer.

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

keyboard throwing that conflicts can cause.





DMA (2)

For example, a sound card may need toaccess data stored in the computer'sRAM, but since it can process the data

itself, it may use DMA to bypass the CPU In order for devices to use direct memory

access, 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

Resources used by virtually every device

in the computer.

Conceptually; they represent locations in

memory that are designated for use by

various devices to exchange information

between themselves and the rest of the

PC.



I/O Addresses Spaces

Unlike IRQ and DMA channels, which are

of 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



Motherboard Fault Symptoms

General Testing(1)



1. Remove unnecessary peripherals (soundcard,

modem, hard disk, etc.) to check the non-working device in as much isolation as

possible.

2. Power supply - Power incompetency (watts

and volts) can cause intermittent problems atall levels.

3. Inspect the motherboard for loose components

(CPU, BIOS chip, Crystal Oscillator, or Chipset

chip).

4. Check for loose or missing jumper caps,

missing or loose memory chips (cache and

SIMM's or DIMM's)

General Testing(2)



General Testing(2)

1. Check the BIOS Setup settings - A quick

fix is to restore the BIOS Defaults.2. Next, eliminate the possibility of

interference by a bad or improperly set

up I/O card by removing all cards exceptthe video adapter.

3. Insert the cards back into the system oneat a time until the problem happens

again.4. When the system does nothing, the

problem will be with the last expansioncard that was put in.

N P !!!



No Power!!!

1. Check the power cable to the wall and

that the wall socket is working.

2. Swap power supply with one that is

known to work.

3. If the system still doesn't work, check for

fuses on the motherboard. If there are

none, you must replace the motherboard.

Peripheral Won¶t Work



Peripheral Won t Work

(New peripheral )

1. Check the MB BIOS setup to ensure thatthe BIOS supports the device and thatthe MB is correctly configured for the

device - when in doubt, reset CMOS to DEFAU LT VALU ES .

2. Check cable attachments & orientation -don't just look, reattach!

3. If that doesn't work, try another peripheral of same brand & model that isknown to work - If the swap peripheral works, theoriginal peripheral is most likely the problem

4. If the swap peripheral doesn't on the MB, verify



the functionality of the first peripheral on a testmachine. If the first peripheral works on

another machine and if the set-up of themotherboard BIOS is verified and if all

potentially conflicting peripherals have beenremoved or verified to not be in conflict, the

motherboard is suspect.5. At this point, recheck MB or BIOSdocumentation to see if there are known bugswith the peripheral and to verify any MB or peripheral jumper settings that are necessaryfor the particular peripheral to work.

6. Try a different peripheral of the same kind buta different make to see if it works

7. If it does not, swap the motherboard

Peripheral Won¶t Work



Peripheral Won t Work

(Peripheral Work Before)

1. If the hood has been opened (or even if it

has not), check the orientation and/or

seating of the cables

2. If that doesn't work, try the peripheral in

another machine of the same make &

bios that is known to work - If the peripheral still

doesn't work, the peripheral is most likely the problem.

3. Swapping-in a working peripheral of the

same make and model - If it works, then the first

peripheral is the problem.

4. If the peripheral works on another hi d bl h k th i h l



machine, double-check other peripheralsand/or potential conflicts on the MB,

including the power supply - if none can be

found, suspect the MB.

5. At this point, recheck MB or BIOS

documentation to see if there are knownbugs with the peripheral AND to verifyany jumper settings that might benecessary for the particular peripheral.

6. Also, try another peripheral of the samekind but a different make to see if itworks. If not, swap the motherboard!

Other indication of a problem



Other indication of a problem

Motherboard

1. CLOCK that won't keep correct time - Be

sure to check/change the battery.

2. CMOS that won't hold configuration

information - Again, check/change the

battery.

Bad Motherboard or obsolete BIOS



1. If the motherboard cannot configure to a

particular peripheral, don't automaticallyassume a bad motherboard, even if the

peripheral checks out on another

machine

2. Check with the board manufacturer to

see if a BIOS upgrade is available.

3. Many BIOS upgrades can be made right

on the MB with a FLASH RAM program

provided by the board maker.



If there any other

motherboard symptoms?

How to identify and to solve

it?

DISCUSS!!!

Unit 2 Motherboard

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