1. CPU & its Components CPU stands for central Processing Unit
Is the brain of the computer
It is the most important component of a computer also called processor.
A computer cannot work without processor.
All computers must have a CPU
CPU performs all operations on data according to the given instruction
Most of work consist of calculation and data transfer.

2. CPU UNITS CPU consists of two main units
ALU ( Arithmetic & Logical Unit)
CU ( Control Unit)
Memory Unit

3. ALU Actual execution of the instructions takes place in this part
It consists of two units
Arithmetic
Logical

4. 1.Arithmetic Unit 2. Logical Unit Basic arithmetic functions such as
Addition
Subtraction
Multiplication
Division
2. Logical Unit
It perform logical operations like comparing two data items to find which data item is > ,== ,< the other

5. Control Unit Cu is an important component of CPU.
It controls all activities of computer system.
It also called the supervisor of the computer.
Memory Unit
Memory Unit mean Main memory which has two types
RAM ROM

6. Buffers
A buffer is a store in the interface between two devices which temporarily stores data which is being transmitted from one to the other.
The buffer is necessary if the two devices work at the different speed.
Sometimes a devices is already busy in executing some instructions.
Example: there are three printing jobs, the printer can print only one job at a time. The OS sends the next two jobs in buffer which is also known as Spooling