The circuit shown below implements a 2-input NOR gate using two 2-4 MUX…
2005
The circuit shown below implements a 2-input NOR gate using two 2-4 MUX (control signal 1 selects the upper input). What are the values of signals x, y and z?
- A.
1, 0, B
- B.
1, 0, A
- C.
0, 1, B
- D.
0, 1, A
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Correct answer: D
The circuit implements a 2-input NOR gate with output C = A + B. The top MUX has inputs x and y, controlled by signal 1; the bottom MUX has inputs A and B, controlled by z. For a NOR gate, when control is 1 (upper input), the output must be A + B. The top MUX's upper input is 1, so x = 0 (since it must output 1 when control is 1). The lower input y = 1. For the bottom MUX, to get A + B when control is 0 (lower input), z must be A. Thus, x=0, y=1, z=A.
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