3. Parts of a CPU

The CPU is a very complicated chip. It consists of billions of transistors which are tiny electronic switches which are either 'on' or 'off'.

The diagram below shows the main parts of the CPU, along with its connections to external components such as RAM, input and output devices.

There are three sections inside the CPU:

• Control Unit
• Arithmetic Logic Unit (ALU)
• Registers

These are described in later pages. There are three main buses connecting all the parts together. These are the Data Bus, which carries the data, the Address Bus which carries information on the location of the data and the Control Bus, which handles commands to control devices such as the hard disk, the monitor and the graphics card.