CPU or Microprocessor

CPU or the microprocessor is the most important hardware component present in every computer. In very simple terms you can call it the brain of the computer. It is the CPU that does all the processing and provides the intelligence for which computers are known for.

The full form of CPU is Central Processing Unit. Normally people think that CPU is the big box which is kept next to the computer screen. But it is not the big box that you see right next to your monitor, rather it is a small chip that is present on your motherboard and it gives all the power to your computer. Look at the diagram below


The CPU can process one instruction at a time. But the speed at which the CPU does the processing is extremely fast as compared to the speed at which humans can process instructions.

CPU speeds

If you are asked a question – What is the speed of the CPU in your computer then what will be your answer?

Do you know the units in which the speed of any CPU is measured? CPU speeds are measured in GHz or MHz. GHz stands for Giga Hertz and MHz stands for Mega Hertz. 1 Giga is 1 followed by nine zeros and 1 Mega is 1 followed by six zeros. This means that if the speed of your CPU is 2 GHz it can process 2 X 10^9 instructions in one second! You can obviously imagine how fast this speed is. Even small CPU’s which are used for building simple computers like your automatic washing machine have their speeds in MHz.

Common brands of CPU

The most common brands of CPUs which are present in your PCs and laptops are Intel and AMD. There are other companies also which manufacture CPUs, but Intel and AMD are the most popular ones.

32 bit and 64 bit CPUs

Apart from CPU speeds the bit size of the CPU is also an important parameter which is taken into consideration when deciding the powser of a CPU. There are mainly two bit sizes which are in demand these days – 32 bit and 64 bit. In the older days CPUs used to be 8 bit and 16 bit. The bit size of CPUs have increased in the multiples of 8.

But what is the meaning of bit size?

A CPU is majorly made up of 3 parts

  1. ALU or Arithmetic and Logic Unit
  2. CU or Control Unit
  3. Registers or internal storage


You can think of registers present inside your CPU as small containers which the CPU uses to store data or instructions temporarily. The bit size of the CPU tells the size of its registers. If your CPU is 32 bit then it means that the size of the registers is 32 bit and the CPU can store 32 bit data or instructions at a time in its registers and if it is 64 bit it can store 64 bit data or instructions at a time. More data and more instructions mean more processing and better efficiency. That’s why 64 bit CPUs are more efficient than 32 bit CPUs.

The amount of RAM which can be accessed by a CPU also depends on its bit size. 32 bit CPU can access 2^32 bytes of RAM whereas 64 bit CPU can access 2^64 bytes of RAM. More RAM in your computer means more efficiency for the CPU.

In the next tutorial we will discuss why the amount of RAM a CPU can access depends on the bit size of the CPU

Knowing the speed and bit size of a CPU is sufficient to know about its capabilities. It will be a good exercise to find out the speed and bit size of the CPU in your PC or laptop to see how powerful your computer is.

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