Write the truth table for circuit given in Figure below consisting of NOR gates and identify the logic operation (OR, AND, NOT) which this circuit is performing

(Hint: then and inputs of second NOR gate will be 0 and hence Similarly, work out the values of for other combinations of and Compare with the truth table of OR, AND, NOT gates and find the correct one.)

Solution:

Input for the circuit: and

For the first circuit, the output is

We can see from the diagram that the second gate’s input is automatically the first gate’s output.

Therefore, the output obtained from this combination can be expressed

Following is the truth table for the given operation: