Control Unit

A control unit is one of the two components of the central processing unit. The function of the control unit is to extract information which is stored in the memory and to decode and execute those instructions. It also takes help from the arithmetic logic unit , whenever required. The control unit is very important for computers functioning . The control unit has outputs which take charge of the activities of the entire device. Some regard the control unit to be an FSM or finite state machine which is used for hardware and software applications.

Control Unit and Microprogram :

There was a time when the manufacturing of control units was a difficult process, especially in designing it. But today the scenario has changed. A control unit is executed in the form of microprograms which remain in control stores. There is a micro sequencer which chooses the words and certain portions of those words which directly manage the various computer parts. These parts are arithmetic and logic units, buses, instruction registers, registers and input/output. Today the latest computers may possess subsidiary controllers for every subsystem, which would be supervised by the main control unit .

Functions of Control Unit:

A control unit can be described as a sort of circuitry that supervises and controls the path of information that runs over the processor and organizes the various activities of those units that lie inside it.

• It carries out many tasks such as decoding, fetching, handling the execution and finally storing the results.

• It controls the execution of instructions in a sequential order.

• It guides the flow of data through the different parts of the computer.

• It interprets the instructions.

• It regulates the time controls of the processor.

• It sends and receives control signals from various peripheral devices.

A control unit is a major computer part which helps in the functioning of the central processing unit and in turn runs the whole computer.