1. AND gate Circuit symbol:
A and B are inputs and Y is the output.
It is a logic gate and hence A, B, and Y can have the (a) Two input AND gate value of either 1 or 0.
Boolean equation:
Y = A.B
It performs logical multiplication and is different from arithmetic multiplication.
Logic operation:
The output of AND gate is high (1) only when all the inputs are high (1). The rest of the cases the output is low. Hence the output of AND gate is high (1) only when all the inputs are high.
2. OR gate:
Circuit Symbol A and B are inputs and Y is the output.
Boolean equation:
A + B = Y
It performs logical addition and is different from arithmetic addition.
Logic operation:
The output of OR gate is high (logic 1 state) when either of the inputs or both are high.
3. NOT gate:
Circuit symbol A is the input and Y is the output.
Boolean equation:
Y = \(\bar A\)
Logic operation:
The output is the complement of the input.
It is represented with an overbar. It is also called as inverter. The truth table infers that the output Y is 1 when input A is 0 and vice versa. The truth table of NOT.
4. NAND gate:
A and B are inputs and Y is the output.
Boolean equation:
Y = Y=\(\overline {AB}\)
Logic operation:
The output Y equals the complement of AND operation. The circuit is an AND gate followed by a NOT gate. Therefore, it is summarized as NAND. The output is at logic zero only when all the inputs are high. The rest of the cases, the output is high (Logic 1 state).
5. NOR gate:
Circuit symbol:
A and B are inputs and Y is the output.
Boolean equation:
Y= A + B
Logic operation:
Y equals the complement of OR operation (A OR B). The circuit is an OR gate followed by a NOT gate and is summarized as NOR. The output is high when all the inputs are low. The output is low for all other combinations of inputs.
6. Ex – OR gate:
Circuit symbol A and B are inputs and Y is the output. The ExOR operation is denoted as ⊕.
Boolean equation:
Y = A. + .B
Y = A ⊕ B
Logic operation:
The output is high only when either of the two inputs is high. In the case of an Ex-OR gate with more than two inputs, the output will be high when odd number of inputs are high.
