The Central Processing Unit

The Central Processing Unit The CPU (Central Processing Unit) is the processor within the

computer.

It is a microchip which carries out all of the searching, sorting,

selecting and calculating within the computer.

The CPU also has an internal clock which determines the maximum speed

at which everything within the computer is done.

CPUs run at different speeds measured in MHz.

The Intel Pentium 4 shown above runs at a maximum of 2.2GHz.

The most common CPUs in PCs are Celeron Processors and Pentium

Processors both made by Intel.

The CPU is plugged into the motherboard enabling it fast access to all

devices especially ROM and RAM chips.

Main Processing Unit Devices - Motherboard

The Motherboard is the heart of the computer, into which everything

plugs.

When you buy a computer it usually has a Motherboard which already has

a CPU, RAM, ROM, Ports and Connecting leads. The Hard Disk Drive and

Floppy Disk Drive are connected directly to the Motherboard.

Usually there are also a number of spare slots to attach additional

devices such as RAM, Sound Cards etc.

These spaces are known as expansion slots.

An advantage of Motherboards is that they make it easier to upgrade an

existing computer rather than buying a whole new PC.

Main Processing Unit Devices - Ports

A port is a point at which you can attach leads from devices to the

Main Processing Unit.

Ports can be at the front or the back of a computer.

The ones in the picture are hidden by a flap at the front of the PC.

Ports are of different types and are of dif...

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...he DVD

rotates and a laser light moves back and forth to read the

information. Information can be stored on both sides of the disk

unlike CD ROM which can only store information on one side.

DVD drives operate at different speeds which means the speed at which

data can be retrieved varies.

The quality of the laser also affects the performance.

DVD ROMs often hold information like movies in an encrypted format.

This is to try and stop pirate copies of copyright material being

made.

Many DVD ROM Drives are fitted inside the casing of the Main

Processing Unit with a cable connecting the drive to the Motherboard.

Once 'pressed' with new data DVD ROMs cannot be erased and refilled

with different data.

It is generally accepted that DVD ROM technology will replace CD ROM

technology in the next few years.