The microcomputer contains a microprocessor, a memory unit and an input/output unit. These elements are explained in the following in detail. The system bus contains three buses. These are the address bus, the data bus and the control bus. These buses connect the microprocessor to each of the memory and I/O elements so that information transfer between the microprocessor and any of other elements can take place.

On the address bus information transfer normally takes place only in one direction from the microprocessor to the memory or I/O elements. Therefore this is called a unidirectional bus. This bus is usually 16 to 32 bits wide. The data bus is a bidirectional bus. This bus is normally 8, 16, or 32 bits wide.