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CPU COMPONENTS

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• The most important part of a PC is the motherboard. It

holds:

– the processor chip

– memory chips

– chips that handle input/output (I/O)

– the expansion slots for connecting peripherals

• Some chips are soldered onto the

motherboard(permanent), and some are removable (so

they can be upgraded).

INTRODUCTION

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Typical motherboard diagram is shown below

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Typically mounted Laptop Motherboard

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Motherboard architectural drawing

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MOTHERBOARD

A Motherboard has major parts such as

1. Processor

2. Sockets

3. Slots

4. North bridge

5. South bridge

6. Peripheral ports

7. Primary memory

8. Secondary memory

9. CMOS memory

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1. PROCESSOR

• This is like the brain of computer, it receives input instructions and processes it to produce the required output.

• Each processor works with particular motherboard with unique processor socket/slot, that is an Intel motherboard will not work with an AMD motherboard.

• The processors will interface with its outside components via FSB, known as Front Side Bus.

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Processor cooling system involves

• Thermal compound, it is a white compound

applied between processor and heat sink

• Heat sink with cooling fins

• Fan

Typical heat sinks with a fan

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Embedded Processor with heat sink mounted.

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2. SOCKETS

• Computer motherboard has the first and its largest socket for

its processors.

• There has been many types of computer sockets such as the

old socket 7 which was the first and the last to work for three

types of processors. Intel, AMD and Cyrix Processors.

• There after each processors from a different maker has a

unique socket for their processors.

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• Typically there are two most commonly used processor sockets PGA (Pin Grid Array) and LGA (Land Grid Array).

• PGA socket has HOLES while Processor has PINS

PGA Socket PGA Processor

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• LGA socket has PINS and processor has grid array CONTACTS.

• For Slot processor mounting system slot has CONTACTS and Processor Mounting board has Dual In Line CONTACTS.

LGA Socket LGA Processor

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IDE or PATA Socket

• The socket mounts the PATA

HDD into the motherboard via

a flat cable.

• The pin number 1 in the flat

cable is denoted by red colour

and a guider such that the drive

connection may be

interchanged.

• The socket colour

distinguishes between primary

and secondary drives and one

socket and one cable may

connect up to two drive in

Master –Slave connections by

jumper settings on the rear of

drive, or cable select

IDE, PATA motherboard socket

14IDE, PATA one end connector. Both ends are alike.

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• SATA Sockets, for this type of

socket the cable is thinner and

contains fewer cables (7) than

that of PATA (40).

• The socket is also smaller than

that of PATA and can connect

a single drive.

SATA Sockets

Section of motherboard showing SATA sockets in yellow colour

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SATA Data cable

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3. SLOTS

1.PCI

• Peripheral Component

Interconnect(PCI) is

a local computer bus for

attaching hardware

devices in a computer.

• PCI Slots, holds system

upgrade PCI Riser cards

Typical Section of

motherboard, PCI slots

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RAM Slot, holds system memory few examples are shown

bellow

Typical section of computer motherboard,

DDR3 RAM slots, there are few more types of

RAM slots

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AGP Slots, Holds VDU Riser card

Typical Computer motherboard section showing AGP

marked with Yellow colour

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Typical AGP graphics card

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• A northbridge or host bridge is a microchip on

some PC motherboards and is connected directly to the CPU and

thus responsible for tasks that require the highest performance.

• Handles communications among the CPU, in some cases RAM,

and PCI Express (or AGP) video cards, and the southbridge.

• Some northbridges also contain integrated video controllers, also

known as a Graphics and Memory Controller Hub (GMCH).

• Also known as external memory controller hub (MCH)

or integrated memory controller hub (IMCH).

4. NORTH BRIDGE CHIPSET

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• The southbridge is a chip in the core logic chipset on

a personal computer (PC) motherboard.

• Implements the slower capabilities of the motherboard in

a northbridge/southbridge chipset computer architecture.

• Handles all of a computer's I/O functions, such as USB,

audio, serial, the system BIOS, the ISA bus, the interrupt

controller and the IDE channels.

• Also known as I/O Controller Hub (ICH), or Fusion

Controller Hub (FCH).

5. SOUTH BRIDGE CHIPSET

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6. PERIPHERAL PORTS

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1. RAM

• Random Access Memory (RAM). RAM is used to hold

programs while they are being executed, and data while it

is being processed.

• RAM is volatile, meaning that information written to RAM

will disappear when the computer is turned off.

• RAM contents can be accessed in any (i.e. random) order.

• By contrast, a sequential memory device, such as magnetic

tape, forces the computer to access data in a fixed order

because of the mechanical movement of the tape.

7. PRIMARY MEMORY

26Structure of Ram

Notches for socket

”Handles”

Socket profile Edge connector

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1. SRAM (Static Random Access Memory)

• SRAM holds data in a static form, as long as the memory has

power.

• Each bit is stored on four transistor that forms two cross

coupled inverters.

2. DRAM (Dynamic Random Access Memory)

• DRAM is called dynamic because it must constantly be

refreshed and lose the data in very short time.

• DRAM stores each bit of data in a separate capacitor within a

integrated circuit.

Types Of Ram:

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How much RAM is Enough?

• Computers typically have between 64 and 512 Mb (megabytes)

of RAM.

• RAM access speeds can be as fast as 8 nanoseconds (8

billionth of a second).

• The right amount of RAM depends on the software you are

using.

• You can install extra RAM.

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Read-Only Memory can be read but not changed.

It is non-volatile storage: it remembers its contents even when

the power is turned off.

ROM chips are used to store the instructions a computer needs

during start-up, called firmware.

Some kinds of ROM are PROM, EPROM, EEPROM, and CD-

ROM.

2. ROM

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1. Hard Disks

• Speed:

Very fast!

The speed of a hard disk is often quoted as "average

access time" speed, measured in milliseconds. The

smaller this number the faster the disk.

• Capacity:

Enormous! Often 40/80 Gigabytes. A Gigabyte is

equivalent to 1024 Megabytes.

• Cost:

Hard disks costs are falling rapidly and normally

represent the cheapest way of storing data.

8. SECONDARY MEMORY

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• Storage Devices -- "How it saves data and

programs“

- - Hard disk drives are an internal,

higher capacity drive which also stores the

operating system which runs when you power

on the computer.-

"Floppy" disk drives allow you to save

work on small disks and take the data with

you.

2. Floppy Drive

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3. CD-ROM Drive

• They are disc drives which read

Compact Discs (CDs). They are

transportable and can be used to

perform various tasks such as

reading data from the computer

and listening to audio.

• Data is written on a CD by

burning pits into the disc to

produce non-reflective areas.

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4. DVD Drives

• Computer DVD drives can be used to watch DVD video, play audio CDs and store information on DVDs and CDs. DVD drives are now being installed in new computers instead of CD drives.

• Computer DVD drives are able to read data stored on CD-ROMS and DVDs and can play both video and audio DVDs. CD-ROM drives cannot read DVDs.

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• A computer needs a semi-permanent way of keeping some start-up data

– e.g. the current time, the no. of hard disks

– the data may need to be updated/changed

• CMOS memory requires (very little) power to retain its contents.

– supplied by a battery on the motherboard

9. CMOS Memory

The battery

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