(i) NOT gate : Not gate is also called inverter. It is an electronic circuit with one input and one output. It produces a ‘1’ output if the input is ‘0’ and vice-versa. The fig. shows the logic symbol and truth table of NOT gate.
(ii) OR Gate : An OR gate has two or more inputs with one output. The logic symbol and truth table are shown in Fig. The output Y is 1 when either input A or input B or both are 1s, that is, if any of the input is high, the output is high.
(iii) AND Gate : An AND gate has two or more inputs and one output. The output Y of AND gate is 1 only when input A and input B are both 1. The logic symbol and truth table for this gate are given in Fig.
