Central Processing Unit is also named the brain of a computer. This is where all the information that is fed into a computer is processed, and the result is obtained. It may also be referred to as processor or processing unit.

What is CPU?

It is an electronic circuit that carries out all the instructions that are given to a computer through the input devices and provides processed information through output devices. It performs basic arithmetic, logical and control functions with the help of a computer program to give the output.

Parts of a CPU

The central processing unit consists of three different parts that together form the CPU. These are:

1. Control Unit: The control unit guides the flow of information within the computer. It accepts information from input devices, passes it on to the memory unit or ALU and once the information is processed, it passes the result on to be displayed by the output device or storage as instructed. The functions of the Control Unit are as follows:

  • Transfer of instructions and data within the computer and its various parts.
  • Co-ordinates the various parts of a computer system
  • It retrieves instructions from the memory, interprets the instructions and controls the functions of a computer.
  • It accepts instructions and data from input devices and displays results on the output devices.
  • It transfers, reads and stores data to and from storage devices.

CU cannot store or process any data on its own. It acts like the traffic policeman who directs traffic on junctions. Here the traffic is data and instructions in the form of electrical impulses.

2. ALU or Arithmetic Logic Unit: This is the part of the CPU where all arithmetic and logical processing take place. It consists of two sections namely:

  • Arithmetic Section: this is responsible for carrying out all arithmetic functions like addition, subtraction, division and multiplication.
  • Logical Section: All logical functions like comparisons, selections, matching, etc. are handled by this part of the CPU.

3. Memory Unit: This is the storage unit of the CPU. All data and instructions that need to be processed are stored here before they are retrieved by the Control Unit and sent to the ALU. Memory unit is more popularly known as RAM or Random Access Memory. It is also called the internal storage, main memory or primary storage. The capacity of the RAM determines the speed, processing power and capability of a computer. The functions of RAM are:

  • All the data and instructions that are needed for processing are stored here.
  • All the results and transitional results are stored here.
  • The outcome of the processing is stored here before being displayed by the output device.
  • All inputs and outputs are routed through the RAM.


In the young age of computers, the CPU was made of different components that could be distinguished easily. Now, the various parts are integrated into one single unit called the microprocessor. These microprocessors are much more powerful and compact than their predecessors. They are now no more than a couple of inches square and are located on the motherboards of the computers. Some popular microprocessors are Intel and AMD

Microprocessors are used in all electronic and digital devices. They are present in the smartphones, tablets, laptops, smart-watches as well as microwave cookers, washing machines, televisions, etc.