Which of the following is a universal gate?
2018
Which of the following is a universal gate?
Answer: B. NAND — Definition: A universal gate can be used to implement any logic circuit. NAND and NOR are universal gates. Using only NAND gates you can implement basic gates…
- A.
NOT
- B.
NAND
- C.
OR
- D.
AND
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Correct answer: B
Definition: A universal gate can be used to implement any logic circuit. NAND and NOR are universal gates.
Using only NAND gates you can implement basic gates as follows: NOT A = NAND(A, A) — connecting both inputs of a NAND to A produces inversion.
AND(A, B) = NAND(NAND(A, B), NAND(A, B)) — a NAND followed by another NAND yields AND.
OR(A, B) = NAND(NAND(A, A), NAND(B, B)) — using De Morgan’s law via NAND-based NOTs gives OR.
Therefore, because NAND alone can produce NOT, AND, and OR, it is a universal gate.
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