How the control unit executes program instructions?

EXECUTION OF INSTRUCTION  

Control Unit controls the operations of all parts of the computer system. It executes the instructions given to the computer. Execution of an instruction by the control Unit consists of four simple steps. These steps are:

(1)Instruction Fetch

It gets a program instruction stored in the main memory of the computer. This is called fetching instruction.

(2)Interpret Instruction

It decodes the instruction to find out what action is to be taken.

(3)Data Fetch

If an decoding requires certain data to operate upon, the CU fetches the data from the computer memory and loads it into a register.

(4)Execute Instruction

After decoding the instruction and getting required data the CU instruction the ALU to process the data according to the given instruction.