T04 - Motherboard

8/6/2019 T04 - Motherboard

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Motherboard


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Motherboards

Motherboard selection determines :

o Types and speeds of CPU you can use

o Chip set on the board

o Types and number of expansion slots

o Types of memory

o Type of case

o ROM BIOS

o Types and number of I/O ports


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Components on the Motherboard

CPU socket/slot

Chipset

Voltage regulating circuit ROM BIOS

Buses and expansion slots

On-board ports and connectors Jumpers and DIP switches


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Integrated / Non-Integrated Motherboard

Integrated Motherboard (Built-in)

All the components or functionalities (such as

graphics, sound, network, modem, I/O controller) are

built into the motherboard If any one of the components fails, you can disable it in

BIOS and replace it with a standalone card with the

same functionality.

Non Integrated Motherboard (Non Built-in) Have each component installed in the computer as

individual expansion card.

Almost all motherboards nowadays are fully built-in

or partially built-in.


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Types of Motherboard Form Factors


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ATX Form Factor Motherboards

Baby AT once were commonly used but has

disadvantage - The processor is in-line with the

memory slot and far from power supply fan. So it

gets heat up very fast. ATX has the processor and the memory slot at the

right angle of the expansion cards, inline with the

fan output of power supply. So it does not get heated

up quickly. SIMM and DIMM connectors are also located away

from drive bays and expansion slots for easier

access.


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CPU Socket/Slot

To host the CPU.

Different sockets/slots are needed for differentCPU (refer back to previous chapter).


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The Chipset

Controls memory, external buses, and some peripherals.

Interconnection between buses uses a hu b interface

architecture

Normally consists of two chips : Northbridge and Southbridge.

Northbridge handles communications between the CPU,

RAM, AGP port orPCI Express, and the Southbridge. Some

Northbridges also contain integrated video controllers.

Southbridge is for other devices such as USB, audio, serial, the

system BIOS, the ISAbus, the interrupt controller and the IDE

channels.

Example : Intel H67 chipset, AMD 870 chipset


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The Chipset

Northbridge

Southbridge


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The Chipset


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CPU Voltage Regulator

Different CPUs require different levels of

voltage on motherboard.

Voltage Regulator Module (VRM) controlsamount of voltage to the CPU.

CPU voltage regulator can be configured via

the BIOS. In older system, it was configured

by jumpers or dip switches.


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ROM BIOS

ROM chip (Read Only Memory) is a non-volatile

storage which cannot be rewritten to. It can only

be rewritten through specific method.

ROM chip is used to store BIOS (Basic InputOutput System) program.


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ROM

There are several types of ROM chips :o PROM (Programmable Read Only Memory)

Can be written to (programmed) via a specific device.PROM can onlybe programmed once.

o EPROM (Erasable Programmable Read Only Memory) Can be erased and rewritten many times.

o EEPROM (ElectricallyErasable Programmable Read-OnlyMemory)

Allow electrically erased and rewritten many times.

o Flash Memory

Same as EEPROM but cheaper.


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BIOS

BIOS refers to the software code run by a computer when first powered on.

The primary function of BIOS is to prepare the machine so other software

programs stored on various media (such as hard drives, floppies, and CDs) can

load, execute, and assume control of the computer. This process is known as

booting up.

The functions of ROM BIOS are :

o Controlling the boot-up procedure

o Performing power-on-self-test (POST) during boot-up

o Generating hardware error codes if a problem found during boot-up

o Finding a boot sector or boot files to boot an operating systemo Providing the most basic commands to control hardware.


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BIOS

A Screen Shot of BIOS


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BIOS UPGRADE

The BIOS program can be u pgraded to a newerversion to su pport newer hardware or to correctbugs.

Two ways to upgrade :

1. Replacing the BIOS chip with newer chip.2. Flashing use special software to upload the new BIOS

software into the chip. This can only be done if the ROMBIOS chip is using flash memory technology. Usually,the new version of BIOS program can be downloaded

from the manufacturer website.

Note : This must be done very carefully else the PCcant be boot at all.


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POST

PowerOn SelfTest.

A set of Diagnostic Program loaded automatically

from ROM BIOS during startup

Designed to ensure that the major system

components are present & operating.

If there is a problem found the POST software writes

an error message to the screen or beep codes will be

heard.

Technician can use this beep codes to recognize the

error.


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CMOS Battery

CMOS (Complementary Metal-Oxide Semiconductor)was used to stored BIOS settings. Battery is required tomaintain the settings so that when the power supplyswitches off, the settings wouldnt lost.

Modern motherboards use EEPROM or flash memoryto store BIOS program and settings. Thus, battery is notnecessary anymore.

Battery is still retained on the motherboard to keep the

real-time clock running.


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CMOS Battery


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Bus

Bus is a set of wires provide interconnection between

peripherals inside the computer.

System bus or Front Side Bus (FSB) connects CPU to

the Northbridge. AGPbus connects graphics card to the Northbridge.

PCI bus connects various expansion cards to the

Southbridge.

USB bus connects external devices to the Southbridge.


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Bus


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Bus Evolution


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Bus Evolution


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Expansion Slots

Most visible part of motherboard. Long plastic slot usually measuring 1 to

11 long.

Are used to attach various types of devicesto expand the capabilities ofPC

2 major types are :1. PCI

2. PCIe / PCI-E

Other types :1. VESA (only in 486 system)

2. ISA (old type)

3. AGP (for graphic cards only)


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ISA-Industry Standard Architecture

Are usually easily recognized by having 2

parts of connector.

Usually brown or black in color

16 bit data path

8 Mhz

Can be found starting from 386 system

until some Pentium IV system.


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ISA Slot


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PCI-Peripheral Component Interconnect

Most motherboard today contains PCI Slot Short, White in color and 3 long

Support 32-bit and 64-bit data path

PCI cards are Plug & Play

Runs at 66Mhz

Can be found in Pentium Class processor Motherboard

or higher.


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PCI Slot


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AGP-Accelerated Graphic Port

64-bit data path

Only used for graphic cards

Directly communicate with video circuit & PC

Memory.

Brown in color, shorter than PCI slot

Located next to PCI slot

Only 1 slot available in all Motherboards

Runs at 66Mhz


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AGP Slot


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PCIe (PCIExpress)

Improved version of PCI

Latest generation of expansion slot

allowing high speed data transfer between

expansion cards and systems.

64 bit data path

Up to 133MHz


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PCIExpress Slot


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VESA Local Bus( VL-BUS)

32-bit data path

Bigger ISA slot (32 bit version of ISA)

High density connector that has lines running

directly to the processor Longer than ISA and have extra 1 connector (32

bit local connector)

Runs at 33Mhz

Only used for a very short period particularlyduring the time of 486 system (1994/1995).


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VESA Local Bus


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Comparison of Slots


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Floppy & Hard DiskConnectors

Floppy, IDE and SATA connector are normally

build onboard nowadays.

On 286,386 & some 486 motherboard this on

board connectors are not available. So theywere using I/O Controller Card which connects

mouse, printer, floppy and harddisk.


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Floppy Drive Connector

Connect the floppy disk

drive and the floppy disk

controller(on-board) with

floppy disk drive cable.

Have 34 Pin


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IDE 1 & IDE 2 Connector

Connect the hard disk

drive (IDE ty pe) or

DVD-ROM drive and

the IDE controller (on-board) with IDE cable.

Each motherboard

normally has two IDE

connector label as IDE1(Primary Controller)

and IDE2 (Secondary

Controller)


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SATAConnector

Connect the hard disk

drive (SATA type)

and the SATA

controller (on-board)with SATA cable.

Each motherboard

normally has two or

more SATA connector


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Keyboard & Mouse Connector

There are 2 main types of keyboard

connectors: AT( Serial) and PS/2.

These connectors are soldered to the

motherboard.

The connectors carries signal from

keyboard to CPU.


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AT Style Connector

A.k.a. DIN-5 Connector

Its round , about

diameter and has 5

sockets or pin. Available in AT type or

order motherboards.


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PS/2 Style Connector

Smaller than AT

connector.

All the PC today

uses PS/2

keyboard &mouse connector.


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Ports

Serial, Parallel, USB & Game Port.

Connecting external device such as modem,

printers, scanners, etc.

Usually soldered on the motherboard.

On older motherboard, ports were using a

dongle connecting to the motherboard pins.


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Serial Port

2 different types 9 pin & 25 pin

A.k.a. DB 9 male or DB-25 male port or

communication port (com port).

Transmit 1 bit at a time.

Maximum cable length 50 feet.


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USB Port

Universal Serial Bus

Transfer rate of up to 480Mbps(USB2.0)

Maximum length of cable is 5

meters. Standard motherboard will have atleast 2 USB ports.

Used for Mouse, Modem, PCCamera, printer, etc.

Can be daisy-chained to connect upto 127 devices.


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Fire Wire

IEEE 1394

Transfer rate of u p to

400Mbps

More expensive thanUSB make it not

popular.

Often used for transferring digital

video into PC.


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A serial port connect to the

motherboard through dongleA serial port directly

soldered to the motherboard


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Ports


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Jumpers and DIP Switches

Use to configure various hardware option or

configuration. Jumpers are used to set various

configuration on the system such as:

CPU voltage, Processor Speed, Bus speed, etc. For example: Pentium processor is running at

60MHz until 200MHz. So you must select the correct

configuration to set the processor run correctly.

This could be done by using the jumpers or DIPswitches on the motherboard.


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Jumpers Function

Jumpers allow the user

to close an electrical

circuit allowing the

electricity to flow through

certain sections of the

circuit board. Generally

the jumpers consist of set

small pins, which can becovered with a small

plastic cap.

J d DIP i h


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Jumpers and DIP switch


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Front panel header

Use to connect speakers, LED, PS-On, ResetButton, HD-LED and etc

Usually the label is written on the

motherboard else you may find in manual.


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Installing

If you put these wires

in reverse, you won't

blow anything up, but

your power LED and

hard drive LED won't

light up.

It doesn't matter

which way your insertthe speaker, reset

switch and power

switch.

T04 - Motherboard

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