Difficulty: Easy
Correct Answer: NOR
Explanation:
Introduction / Context:
Schematic “bubbles” indicate logical inversion. Recognizing bubble-pushing patterns and applying DeMorgan’s theorems enables quick translation between gate symbols and their equivalent logic functions, which is crucial in reading or redrawing schematics.
Given Data / Assumptions:
Concept / Approach:
The function of an AND gate with complemented inputs is Y = A’ · B’. DeMorgan’s theorem states that (A + B)’ = A’ · B’. Therefore, A’ · B’ equals (A + B)’. The latter is precisely the definition of a NOR gate.
Step-by-Step Solution:
Write the AND-with-bubbles expression: Y = A’ · B’.Apply DeMorgan: A’ · B’ = (A + B)’.Recognize that Y = (A + B)’ is a 2-input NOR function.Hence, the composite symbol performs as a NOR gate.
Verification / Alternative check:
Construct a truth table for A’ · B’ and compare with NOR(A, B); they match for all input combinations.
Why Other Options Are Wrong:
NOT: a unary operation; our function depends on two inputs.OR: would be Y = A + B (no inversion).NAND: corresponds to (A · B)’ which is different from (A + B)’.
Common Pitfalls:
Forgetting that bubbles invert signals and that DeMorgan converts between AND-of-complements and complement-of-OR.
Final Answer:
NOR
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