If X and Y are the inputs, the given circuit works as . [figure]
- OR gate
- AND gate
- NAND gate
- NOR gate
Answer
(4) NOR gate
Solution
A NAND gate with its two inputs joined gives A A = A, i.e. it acts as a NOT gate.
First stage: outputs X and Y
Middle NAND: X Y = X + Y (De Morgan's theorem)
Last NAND (inputs joined, NOT): output = X + Y
∴ The circuit works as a NOR gate.
Answer: (4)