Universal logic gate

universal logic gates

1. The Universal Property of NAND and NOR Gates NAND and NOR gates are “universal” because they can used to produce any of the other logic functions.

2. NAND GATE A NAND gate is quite the reverse an AND gate (hence the nomenclature) and gives an output of 1 or True only if both the inputs are not True or 1. This means that even when both inputs are 0 or False, it still gives a True or 1 output.

3. NAND Gate - Symbol & Truth Table

4. The Universal Property of NAND Gates NAND Gate as an Inverter The below diagram is of a two input NAND gate. The first part is an AND gate and second part is a dot after it represents a NOT gate. So it is clear that during the operation of NAND gate, the inputs are first going through AND gate and after that the output is reversed and we get the final output.

5. The Universal Property of NAND Gates Two NAND Gates as an AND Gate The above diagram is of an AND gate made from NAND gate. So we can see that all the three basic gates can be made by only using NAND gates, that’s why this gate is called Universal Gate and it is appropriate.

6. The Universal Property of NAND Gates Three NAND Gates as an OR Gate The above diagram is of an OR gate made from combinations of NAND gates, arranged in a proper manner. The truth table of an OR gate is also given beside the diagram. Now we will see the design of an AND gate from NAND gates.

7. NOR GATE A NOT gate followed by an OR gate makes a NOR gate. NOR gate means not an OR gate which means output of this gate is just reverse of that of a similar OR gate. We know that output an OR gate is 0 only when all inputs of OR gate is 0. But in the case of NOR gate the output is 1 only when all inputs are 0. In all other cases, that is for all other combinations of inputs the output is 0.

8. NOR Gate - Symbol & Truth Table

9. The Universal Property of NOR Gates NOR Gate as an Inverter The above diagram is of a NOT gate made by using a NOR gate. The circuit diagram is similar to that of NOT gate made by using only NAND gate.

10. The Universal Property of NOR Gates Two NOR Gates as an OR Gate The above diagram is of an OR gate made by only using NOR gates. The output of this gate is exactly similar to that of a single OR gate. As we can see the circuit arrangement of OR gate using NOR gates is similar to that of AND gate using NAND gates.

11. The Universal Property of NOR Gates Three NOR Gates as an AND The above diagram as the name suggests is of AND gate using only NOR gate, again we can see that the circuit diagram of AND gate using only NOR gate is exactly similar to that of OR gate using only NAND gates. Now we will finally see how a NOT gate can be made by using only NOR gates.