What does the CPU do?

Carries out instructions and tells the rest of the computer system what to do. This is done by the Control Unit of the CPU which sends command signals to the other components of the system.

Performs arithmetic calculations and data manipulation, eg. comparisons, sorting, combining, etc. The computer's calculator is a part of the CPU known as the Arithmetic Logic Unit.

Holds data and instructions which are in current use. These are kept in the Main Store or Memory.

To understand how the whole system works, consider the diagram shown below. This diagram shows the basic components of a generalised CPU. An actual CPU may have these components, or other with different names that provide the same functions.

Click on the different units of the CPU to learn more about them.