The part of a computer that performs huge number of data processing operations is called CPU. The CPU is also referred as to CENTRAL PROCESSING UNIT. The CPU of a computer has three important parts namely register set, ALU (Arithmetic Logic Unit) and CU (Control Unit). The CPU of a computer is like the brain of the computer. As in human being brain is major part of the body because it is responsible for the functioning of the all other part of the body. The brain also takes all decisions. Similarly the CPU of a computer does these things. The register set stores intermediate data used during the execution of instructions. The ALU takes care of handing for execution of all micro operations for executing the instructions. And finally the control unit supervises the transfer of information among registers and instruct to the ALU as to which operation to perform.


As we have can see above in the picture the CPU of a computer is made of three major parts as discussed here.

  1. Register set
  2. Arithmetic logic unit
  3. Control unit


As the instructions are interpreted and executed by the CPU, there is a movement of information between the various components of the computer sMAJOR COMPONENTS OF CPUystem. To handle these processes satisfactorily and speed up the computer system special kind of memories are used which are called registers. Registers are not the part of the main memory. Registers are used as temporary storage. The number of register varies among computers. Many computers use several types of register, each of which has its own specific work. Different types of register used in computers are listed here.

  1. Data Register
  2. Address Register
  3. Accumulator
  4. Instruction Register
  5. Program Counter
  6. Temporary Register
  7. Input Register
  8. Output Register


ALU is the unit of a computer where actual execution of instructions takes place. The control unit of the CPU supervises the ALU to execute the instruction. The ALU of a computer take care all logical and arithmetical decisions. To be more precise, all calculations are performed and all comparisons are made in the ALU.


To know more about control unit we must be known with some question before and these questions are as:

  • How does input device know that it is time for it to feed data into the storage unit?
  • How does the ALU know that what should be done with data one they are received?
  • How does the output device know that it is time to show the output?

The answer of these questions is that all these are possible because of the control unit of the computer system. The control unit of a computer system can select, interpret all instruction. Control unit can also determine the order of execution of the instructions. Actually it does not perform any work but supervises other unit how to perform tasks. The control unit of a computer system is like the nervous system which sends signal to other and receive signal from others. It managesĀ  and coordinates the entire computer system.

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