Control unit (CO)

The control unit of the CPU directs the entire computer system to carry out or rescued stored program instruction you can compare the control you need to a police officer directing traffic at a busy intersection but instead of directing cars the control unit directs data flow between the computer processor memory and input output devices.
The CPU performs following four steps in executing instruction:-

1.   The control unit gets the instruction from memory.
2.    The control unit decides what the instruction means and directs the necessary data to be moved from the memory to the arithmetic logical unit.
3.    The arithmetic logical unit performs the actual operation on the data.
4.    The result of the operation is stored in memory or register.