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

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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.

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Ports are of different types and are of different shapes and sizes

A few examples are:

Main Processing Unit Devices - Modem

Modems can be External (connected by a lead to a Port) or Internal (fixed to a slot on the Motherboard)

A modem allows a computer to send and receive data through a telephone line.

Modems transmit data at different speeds known as Baud Rate.
Speed is measured in
Bits per Second or bps.

It is common for modems in the home to transmit and receive data at 56 Kbps.

External modems are becoming less common because most new computers come with ...

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