The control unit is primarily responsible for directing all the activities of the computer. It also manages interactions between the other components in the computer system. In addition, the control unit contains both hardwired instructions (called microcode or microprograms) to perform operations. An example of an instruction might be the command to fetch information from memory. In older systems, the control unit would be a large number of integrated circuits on a circuit card. On a microprocessor-based system, the control unit is part of the microprocessor.
I the control unit determines when the user's commands will be proccessed.