What is a CPU? Explain the different parts of a CPU.

CPU is the main unit of a computer. It controls all the internal and external devices of a computer and performs arithmetic and logical operations. CPU is very small and is referred to as a microprocessor.

There are mainly three components of a CPU:

1. Memory Unit (MU) — The memory unit is the principal storage of the computer. It stores both data and instructions. Computer memory is classified into two categories:
   i. Internal Memory — It stores data and programs temporarily as long as they are being executed. It is very fast and expensive but has limited storage capacity. For example, RAM and ROM.
   ii. External memory — It stores data and programs permanently. For example, hard disk, CD/DVD etc.

2. Arithmetic and Logical Unit (ALU) — All the arithmetical and logical operations are performed through this unit. An arithmetical operation includes addition, subtraction, multiplication, division and logical operations include all types of comparisons.

3. Control Unit (CU) — This unit controls each and every part of the computer system along with the peripherals. It extracts the instructions from memory, decodes them and sends the necessary signals to ALU to perform the required operation. It is also called the central nervous system of a computer system as it manages all other units.