Block Diagram Of Computer: 

A computer is designed using four basic units, they are:

1. Input Unit.

2. Central Processing Unit (CPU).    

     (a) Control Unit.    

     (b) Arithmetic and Logic Unit.

     (c) Registers.

 3. Memory Unit.

 4. Output Unit.

Input Device:Computers need to receive data and instruction in order to solve any problem. The Input Unit performs this operation. The input unit basically links the external world to the computer. The input unit consist of one or more input devices.Example:Keyboard, mouse.

Central Processing Unit (CPU):The CPU is known to be heart or brain of he computer system and the program to manipulate data into information.

Control unit: Control Unit refers to a functional unit which carries out four basic operations.

1.Fetches an instruction.

2.Decode the instruction.

3.Executes the instruction.

4.It stores the results.

Arithmetic Logic Unit: Arithmetic Logic Unit performs arithmetic and logic operations and controls the speed of these operations.Logic operations are like AND, OR, NOT.

arithmetic operations are like addition, subtraction, multiplication and division.

Register: Registers are high speed storage areas that temporarily store data during processing to enhance computer's performance.

Memory Unit: Memory Unit is an essential component of any digital computer, It is a storing device. It stores programs and data, which are required by the CPU, and the result after processing.

Output Devices:The output unit converts the data from binary form to the human understandable form before it displays the result.