Truth Table: A table that shows all the inputoutput possibilities of a logic circuit is called a truth table. There are several types of the truth table.AND, OR, NOT, NAND, NOR, XOR, XNOR Gates are described below:
(a) AND Gate: In English language, Input A is ANDed with Input B to get output Y.
The truth table illustrates four ways to express the logical ANDing of A and B. The AND Gate works on the principle that output will be high when all the inputs are high otherwise output will be low.
(b) OR Gate: In OR Gate, input A is ORed with input B to get output Y.
The OR Gate works on the principle that, if anyone input is high, the output will be high. Thus, the only case when output will be low is when all inputs are low i.e., 0. (c) NOT Gate: The NOT Gate is an electronic circuit that generates an output signal which is the reverse of the input signal. A NOT gate is also known as an inverter because it inverts the input.
(d) NAND Gate: A NAND Gate is a complemented AND gate. That is, the output of NAND Gate will be 1 if anyone of the inputs is 0 and will be 0 when all the inputs are 1.
(e) NOR Gate: A NOR Gate is a complemented OR Gate. That is, the output of a NOR Gate will be 1 only when all inputs are 0 and will be 0 if any input represents a 1.
(f) XOR Gate (Exclusive-OR Gate): XOR Gate is a combination of AND, OR, and NOT Gates. symbol denotes XOR operation. This Gate works on the principle that if an odd number of inputs are 1, the output will be 1 otherwise output will be 0.
As observed from the truth table, the output is 1 when odd numbers of inputs are 1.
(g) XNOR Gate (Exclusive-NOR Gate): Similarly, XNOR gate is also formed with a combination of AND, OR, and NOT gates. symbol denotes XNOR operation. Since this gate is the inverse of XOR gate, the output will be 0 when odd numbers of inputs are 1 otherwise output will be 1.
