uniti the following figure shows the symbol of an or gatewhich is having two inputs ab and one outputy the following table shows the truth table of -input or gate = + universal gates nand nor gates are called as universal gates because we can implement any boolean functionwhich is in sum of products form by using nand gates alone similarlywe can implement any boolean functionwhich is in product of sums form by using nor gates alone nand gate nand gate is digital circuit that has two or more inputs and produces an outputwhich is the inversion of logical and of all those inputs the following image shows the symbol of nand gatewhich is having two inputs ab and one outputy the following table shows the truth table of -input nand gate department of csevishnu institute of technology