Can Anyone Explain The Working Of Control Unit (CU)?

Control Unit is also called Brian of the computer and controls all the activities of processor. Control unit (CU) decodes and executes the instruction one by one.  Computer Programs are when loaded into the main memory, each instruction is stored in address register. Control Unit (CU) reads the address of first instruction load in the memory of computer through address register.

Then control unit fetches the instruction through buffer register and send this instructions to the instruction register. The instruction register decodes the instruction and executes it by sending command signals to related units or circuits. Program counter is also called counter register that is use to point the instruction that is to be executed next.  It counts the instructions of the program that have been executed. The value in the program counter increases by one after executing an instruction.


Control unit (CU) also control the functions of input and output devices. It gets input from input devices through input and output register and stores it into the memory of computer. After an instruction is to get from an input unit during program execution, then instruction register decodes the instruction and send command to the input unit.