MotherboardsSystems ManagementFreedom High School

Objectives

Identify major parts of motherboard Identify common motherboard form

factors Explain motherboard bus architecture Identify expansion slot architectures

Objectives

Identify import system resources Identify and explain IRQs Explain the role of a chipset Explain the purpose of the CMOS Explain the procedure for upgrading a

Flash BIOS

The “Mother” of all Boards

Most important element of a computer All major components connect to and

transmit data across Communication central for input/output Provides the means for expanding and

customization Also Known As:

system board, main board, planar board

Construction

Provides the physical surface for electronic components

Constructed mainly of electrical insulation material

Covered with small electrical circuits called traces

Terminology

bus collection of conductors that connect

multiple components data bus

used to move data between components

control bus delivers command signals from

processors to devices

Terminology

memory bus connects the processor to the

memory I/O bus

connect the processor to the expansion slots

internal bus part of the integrated circuit inside

the CPU

Terminology

local bus connects directly to the CPU provides communications to high-

speed devices mounted closely to the CPU

address bus connects CPU with main memory

module identifies memory locations where

data is to be stored or retrieved

Form Factors

Physical shape or outline of the motherboard

XT, AT and Baby AT Original IBM PC used the AT XT (8-bit) and Baby AT (16-bit) same size

ATX Introduced in 1996 Incompatible with most other form factors Turned 90º from other board Power supply different shape

Form Factors

LPX Low profile desktops or narrow towers Expansion cards attached to a bus riser card

NLX Similar to the LPX Riser card at the rear Specialized for industry and becoming the

standard ATX and NLX most popular w/

manufacturers

Form Factors

BTX Latest form introduced for the PC

market Designed to meet the need for better

cooling and acoustics. Reduced noise levels Three system sizes

BTX microBTX nanoBTX

BTX Form FactorOutstanding acoustic and thermal improvements

Improved air flow for better cooling – 5 to 10 degrees cooler than an ATX system

Only a single fan is needed, reducing noise, heat, power consumption and system size

Bus System Architecture

Originally quite simple One bus connected the everything

CPU

ISA bus 16-bit / IBM XT bus 8-bit 4.7 MHz

Keyboard

Diskette Drive

LPT

ISA Expansion Slot

ISA Expansion Slot

ISA Expansion Slot

Bus System Architecture

Bus System Architecture

Technology improved CPUs speed surpassed the

capabilities of the bus Chipsets provide communication

between buses of different speeds North bridge handles the RAM/Video

(AGP) South bridge handles expansion slots,

I/O ports

Bus Speed Architecture

CPU bus is fast because it is short◦ Microscopic

Bus systems are slower◦ Longer, suffer from inductive reactance

Because of the speed differences the CPU must go into a state of rest◦ Commonly referred to as wait state

Expansion Card Slots

Quick and easy way to connect to the bus

Allows customization Several styles

ISA, EISA, MCA, VESA, PCI, AGP, AMR, CNR, USB, and IEEE 1394

Expansion Cards

Industry Standard Architecture (ISA) 16-bits wide with a bus speed of 8.33

MHz originally designed by IBM as 8-bit 4.77

MHZ ISA is used for internal ports

keyboard, mouse, diskette drive, parallel port

Only bus system left on PC motherboard for backward compatibility

Expansion Cards

Micro Channel Architecture (MCA) 32-bit data bus Not physically compatible with ISA Could assign IRQs without human intervention Proprietary to IBM

Extended Industry Standard Architecture (EISA) Joint development to avoid royalties Physically compatible with ISA

Expansion Cards

• Video Electronics Standards Association (VESA)• Developed by a consortium of video adapter and

monitor manufacturers• The VESA bus could handle faster speeds than MCA

or EISA• Became obsolete as CPU speeds increased

• Peripheral Components Interface (PCI)• Best choice for general purpose expansion• Network servers were the first to use PCI• There are now faster versions

Expansion Cards

• PCI Extended (PCI-X)• Replaced PCI at 64-bit data width• Faster data transfer, PCI-X 1.0 ix 133 MHz

Bus Type Speed Capacity

PCI-X 1.0 133 MHz 8.5 Gbps

PCI-X 2.0 266 MHz 17 Gbps

PCI-X 2.0 533 MHz 34 Gbsp

Expansion Cards

• PCI Express (PCIe or PCI-E)• Designed to replace earlier versions of PCI, PCI-X and AGP

• Uses serial data transfer • Original PCI used parallel data transfer

• Parallel data transfer is better than serial at slow speeds

• Serial data transfer is preferred at higher speeds

Expansion Ports

• Parallel Ports• Introduced as high speed• Designed as unidirectional, used for output only

• Bi-directional port was introduced to allow input

• Common parallel port devices:• Printers, scanners, faxes, etc.

Expansion Ports

Universal Serial Bus (USB) Replaced a variety

of ports and expansion slots Designed as a port

rather than a slot Can carry limited

electrical power Up to 127 devices

can be connected

Expansion Ports IEEE 1394

(FireWire) Introduced by Apple Can serve up to 63

devices on a single port Since the introduction

of 1394 and USB manufacturer’s have been reducing the number of expansion slots

Expansion Ports

Accelerated Graphics Port (AGP)◦ Exclusively designed for video cards◦ Usually only a single slot on any motherboard◦ Much faster than PCI◦ Offered excellent support until introduction of PCIe

AMR, ACR, and CNR◦ Combining the functions of several separate technologies into a single unit saves money

System Resources

Resources assigned and made available Assignments can be viewed under the

Device Manager in Windows I/O Port◦ Memory address expressed in hexadecimal◦ Indentifies a computer device, i.e. video card

Memory Address Range◦ Section of memory used a temporary storage area

System Resources

Interrupt Request (IRQ)◦ Signal that interrupts the processes taking place in

the CPU◦ IRQs are assigned priorities Low number, high priority

◦ Originally only 8 were used ◦ Evolved to 16, made possible by cascading IRQ 2 to

IRQ 9◦ Each IRQ could have multiple devices assigned This meant conflicts and non-working devices

◦ Plug and Play (PnP) remedied most of the assignment problems

System Resources

While I/O address and IRQs can vary from computer to computer, you need to

memorize the following for the A+ test

COM IRQ I/O Address

1 4 3F0-3FF2 3 2F8-2FF3 4 3E8-3EF4 3 2E8-2EF

LPT1 7 378-37F

System Resources

Direct Memory Access (DMA)◦ Combination of software and hardware to allow certain system devices direct access to RAM◦ Eliminated every bit having to go through the CPU◦ DMA settings can be viewed through the Properties dialog box for a system device

Bus Mastering

Allows data to be transferred between two devices without CPU intervention

Different than DMA Bus Mastering takes control of the

connected bus DMA is used to access the memory

system Both designed to speed up common

operations

Chipsets

Designed to handle data manipulation otherwise need to be handled by CPU

Major chipsets ◦ North bridge high speed devices RAM, DVD, and graphics

◦ South bridge slower speed devices Keyboard and mouse

There are other chipsets that handle additional functions

Without chipsets, the CPU would have to handle all computer data through its core

Plug and Play (PnP)

Automatic assignment of system resources◦ DMA channels, interrupts, memory, port assignments

No need to manually configure the system resources

Works most of the time, but not all of the time

BIOS and CMOS

Terms are used interchangeably but they are different

BIOS is a read only memory (ROM) chip◦ Contains machine language software programs

CMOS is a low-power consuming semiconductor chip (complementary metal oxide semiconductor)

BIOS

Initiates Power On Self Test (POST) Initiates the CMOS Setup program Initiates communication between system

hardware and operating system Controls the sequence of boot devices Can password protect CMOS Setup

program◦ Prevents BIOS settings from being changed◦ Can be cleared if password is forgotten

Upgrading BIOS

Fairly common for both hardware and software needs

On early motherboards the BIOS chip had to be physically removed◦ Chip was referred to as programmable read-only memory (PROM)

Or an ultraviolet light had to be used to erase the program◦ Chip had a transparent window through which a transparent light shined through the window the circuitry would be erased

Upgrading BIOS

Modern PC use flash BIOS◦ Electrically erasable programmable read only memory (EEPROM)◦ Easily erased and reprogrammed using software usually available through the manufacturer’s web site

Details will vary depending on the manufactor

CMOS Setup Program

A program that identifies the hard drive and other storage systems in the PC

Setup a password for accessing the PC and CMOS Setup Program

Select certain power management features

Set the boot order of bootable devices

Power On Self Test (POST)

Simple diagnostic program Initiated when electrical power is applied Verifies that the major components are

installed and in working order Varies somewhat by manufacturer◦ Usually checks the CPU, ROM, RAM, keyboard, monitor, mouse, and hard drive

“Beep Codes” will indicate if an error is found

Motherboard Component Identification

Troubleshooting Motherboards

Most expensive part to replace Most difficult to diagnose Often times requires third-party

diagnostic hardware or software Substitution can sometimes be used as a

diagnostic method, but can get expensive Sometimes re-installation will solve the

problem Wires may be loose or crimped

Summary

Motherboard form factor describes the shape and size

Expansion slots include ISA, EISA, MCA, AGP, PCI, and PCIe◦ Newer motherboards no longer include ISA, EISA, or MCA slots

Development of USB and Firewire has reduced the number of PCI slots required

USB 1.1 supports data transfer rates of 1.5 Mbsp and 12 Mbsp

USB 2.0 supports rates as high as 480 Mbps

Summary

System resources include◦ I/O port address◦ Memory address range◦ Interrupt Request (IRQ)◦ Direct memory access (DMA)

DMA allows devices to communicate directly with the memory system without the intervention of the CPU

Bus mastering allows devices to communicate with each other without the intervention of the CPU

Summary

Chipsets combine many individual electronic systems into one or two chips

North bridge controls communication between high speed modules

South bridge controls slower communications

Plug and Play (PnP) automatically detect new hardware and assigns system resources

BIOS performs POST, CMOS Setup, and communication between hardware and OS

Summary

The CMOS chip stores information such as time, date, and type of hard drive

POST test the major components (video, keyboard, mouse, memory, etc.) to see that they are installed and working

MotherboardsSystems ManagementFreedom High School