CP1610:Introduction to Computer Components

The Motherboard

What is the Motherboard?

The largest circuit board in a computer. The means by which all devices are

connected to each other, and the CPU. Also called the system board.

Parts on a Motherboard

What is the CPU

Central Processing Unit. Also called the processor or the

microprocessor. The most important chip in the computer. The brain, or command centre.

Parts of the CPU

Input/output (I/O) unit

Arithmetic logic unit(s) (ALU)

Control unit

How the CPU Works

Please wait until the road is clear, and I will

open the gate!

The I/O Unit is like the security guard at the front gate.

You need to go to Building 10!

The Control Unit (CU) is like a security guard directing students to the correct building.

Parking

Parking

(Internal Cache)

(Registers)10 9

ALU ALU

CISC vs. RISC Processors

CISCComplex Instruction Set Code

RISCReduced Instruction Set Code

CISCRISC

Other Parts on the Motherboard

System Bus CMOS BIOS The Chipset System Clock Expansion Slots Floppy and Disk Drive Connections Memory

System Bus

Metal lines (traces) connecting parts on the motherboard.

Allow data to travel between devices and the CPU.

Like a system of roads throughout a city. Can be expanded to other parts (like

highways connecting towns and cities).

CMOS

Chip that saves your system settings:Date and timeHardware configurationBoot device order

Has a battery so that it can save your settings even when the computer is off

CMOS stands for Complex Metal Oxide Semiconductor

BIOS

Basic Input/Output System Stores basic instructions on how the computer

can talk to: Keyboard Mouse Monitor Memory

Allows a computer to operate basic functions without any other software installed

Is the same for ALL computers.

The Chipset

The chipset controls most parts of the computer.

It handles ‘routine’ work, so the CPU can handle more important processing.

Some of the chips in the chipset include: Interrupt ControllerKeyboard ControllerDMA Controller

The Interrupt Controller

What is an Interrupt?Lots of devices want to get the CPU’s

attention;An interrupt is a signal that tells the CPU

which device is calling, or sending data;The Interrupt Controller is a chip that controls

the flow of data on the system bus, and lets the CPU know which device needs it;

Who is trying to call me? This better

be important!

Don’t worry… I can direct

traffic for you!

The CPU(Everyone wants his attention!)

The Interrupt Controller is like a police offer directing traffic at a busy roundabout.

Some devices get priority over others

How the Interrupt Controller Works

CPU1

2

0

3

4

5

7

6

8

9

11

10

13

12

14

15

System Clock

Keyboard

Floppy

PS/2 Mouse

Inte

rrup

t Co

ntro

ller

Inte

rrup

t Co

ntro

ller

Common Interrupt Requests (IRQ’s)

IRQ USUAL FUNCTION/DEVICE

0 System Timer

1 Keyboard

2 2nd IRQ controller

3 COM2:

4 COM1:

5 Free (used by LPT2: or sound card)

6 Floppy disk

7 LPT1:

8 Real Time Clock (RTC)

9 Free (may be labeled/appear as IRQ 2)

10 Free (often used by sound cards)

11 Free

12 PS/2 mouse

13 Math coprocessor on CPU (used)

14 Primary IDE

15 Secondary IDE

Keyboard Controller

The Keyboard Controller provides the following functions:Keyboard Control and Interpretation.PS/2 Mouse Support.Access to the High Memory Area.

The Keyboard Controller is often not needed in newer computers.

The DMA Controller

Direct Memory Access Sometimes devices may want to ‘talk’ to

each other without ‘going through’ the CPU.

DMA Controller controls access to the system bus, and RAM, and bypasses the CPU.

I’m busy with official business… don’t bother

me!

Thanks, officer. I guess I don’t need to bother with

this car!

The CPU(Not everyone needs his attention!)

The Interrupt Controller

Some devices don’t need to talk to the CPU

I’m only going to McDonald’s! Do I really need to go see the CPU

first?

Don’t worry, Sarge! I’ll direct this car through the

roundabout!

The DMA Controller is like a second traffic officer who handles traffic not going to the CPU

This better be important if you want to keep going down

Madinat Khalifa!

Can I go now?

Beep! Beep!

The System Clock

Crystal that emits a pulse/signal.

Acts like a drummer in a rock band.

Pulses provide timing for the CPU and other devices.

Clock Speeds

Measured in HertzCycles per second

Speed of the Motherboard:Megahertz (MHz)

Speed of the CPU:Gigahertz (GHz)

Expansion Slots

Allow you to ‘expand’ the capabilities of your computer.

Connect new circuit boards to your motherboard.

Connect the data buses (roads) on the expansion cards to the system bus (roads) on the motherboard.

Common Expansion Cards

Sound Cards Modems Network Cards Video Cards Specialty Cards

Types of Expansion Slots

ISA Industry Standard Architecture Older, ‘legacy’ cards

PCI Peripheral Component Interconnect Newer, faster expansion cards

AGP Accelerated Graphics Port

Floppy and Disk Drive Connections

Special slots for ‘ribbon’ (data) cables. Allow you to connect:

Floppy disk drives;Hard disk drives;CD/DVD drives;Zip disk drives;Etc…

Floppy Drives

There is usually only one floppy disk drive connection.

A floppy controller chip on the motherboard controls talking to, and fuctions of the floppy drive.

EIDE Connections

Used to connect:Hard disk drives;CD/DVD drives;

Two connectors on the motherboard.Each connector can connect two devices;Up to four EIDI devices can be connected;

Memory Devices

Hold data and instructions. Types of Memory:

System Memory;RAM;ROM;

System Memory

1 Megabyte (1 MB) Built into motherboard. Maximum memory that could be handled by:

Older PC’s; New PC’s before system drivers and OS are booted;

Hold data and instructions for: System drivers; Programs used by the user;

Available to the user for any software

Reserved for device drivers and system functions

Anything above 1 MB

RAM vs. ROM

RAM Random Access

Memory Stores data and

instructions Volatile

Examples: RAM chips CMOS

ROM Read Only Memory Stores basic system

settings Non-volatile

Example: BIOS

Types of Motherboards

Choice of motherboard affects:Capabilities and limitations of system;Type of computer case needed;

Common types of motherboards:ATATXBackplane

The AT Motherboard

Smaller Used for classic

Pentium CPU Uses SIMM RAM Uses P8 and P9

power connectors

The ATX Motherboard

Faster Easier to install More power

management features Uses DIMM RAM Has a PI power

connector

Backplane Motherboards

Actually built into the computer case. More difficult to make upgrades. Not as popular.