OR gate performs ORing operation on two or more inputs. The OR operation on two independent logic variables A and B is represented as Y = A+B. The output of an OR gate is LOW only when all of its inputs are LOW. For all other possible input combinations, the output is HIGH. The output of an OR gate is a logic ‘0’ only when all of its inputs are at logic ‘0’. For all other possible input combinations, the output is a logic ‘1’. Figure shows the circuit symbol and the truth table of a two-input OR gate. The operation of a two-input OR gate is explained by the logic expression Y = A+B
