Basic Logic Operation.

There three basic Logic operation in digital circuit. They are

1. AND Operation
2. OR Operation
3. NOT Operation

Each operation will have special symbol. The lines connected to each symbols are inputs and outputs. The inputs are on left side of symbol and output is on right side.

A circuit that performs a specified logic operation is called a logic gate.

1) AND Operation:

in AND Operation, if all the inputs are 'HIGH' then it generates 'HIGH' output, otherwise it generates 'LOW' output. It accepts two or more than two inputs and generates single output.

Truth Table:

If A and B are two inputs and Z is the output then Truth table is given as

Inputs		Output
A	B	Z=A.B
HIGH (1)	HIGH (1)	HIGH (1)
HIGH (1)	LOW (0)	LOW (0)
LOW (0)	HIGH (1)	LOW (0)
LOW (0)	LOW (0)	LOW (0)

2) OR Operation:

In OR operation, if  any of the inputs are 'HIGH' then it generates 'HIGH' output, otherwise it generates 'LOW' output. It accepts two or more than two inputs and generates single output.

Truth Table:

If A and B are the two inputs and Z is the output then the Truth Table is given as

Inputs		Output
A	B	Z=A+B
HIGH (1)	HIGH (1)	HIGH (1)
HIGH (1)	LOW (0)	HIGH (1)
LOW (0)	HIGH (1)	HIGH (1)
LOW (0)	LOW (0)	LOW (0)

3) NOT Operation:

In NOT Operation, if the input is 'HIGH' then it gives 'LOW' output and if the input is 'LOW' then it gives 'HIGH' output. It accepts single input and generates single output.

Truth Table:

If A is input and Z is output then the truth table can be expressed as

Input	Output
A	Z=A‘
HIGH (1)	LOW (0)
LOW (0)	HIGH (1)