Question

Using truth table of AND gate and NOT gate , show that NAND gate is an AND gate followed by a NOT gate. Hence write the truth table of NAND gate. Why are NAND gates called 'Universal Gates' ?

Answer 1

Truth Table of NAND Gate

$A$	$B$	Output of NAND Gate
$0$	$0$	$1$
$1$	$0$	$1$
$0$	$1$	$1$
$1$	$1$	$0$

All primary gates likes AND , NOT and OR gates can be realised by using NAND gate only. Hence , it is a universal gate.