Consider the following combinational function block involving four Boolean…
2014
Consider the following combinational function block involving four Boolean variables \(x,\:y,\:a,\:b\) where \(x,\:a,\:b\) are inputs and \(y\) is the output.
f(x, a, b, y) { if(x is 1) y = a; else y = b; }
Which one of the following digital logic blocks is the most suitable for implementing this function?
- A.
Full adder
- B.
Priority encoder
- C.
Multiplexer
- D.
Flip-flop
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Correct answer: C
Answer: Multiplexor (2:1) is the most suitable block.
Key idea: Use x as the select input to choose between data inputs a and b.
Boolean expression: y = x·a + x'·b
Implementation note: A 2:1 multiplexer implements this as y = (x AND a) OR (NOT x AND b), which exactly matches the if(x is 1) y = a else y = b behavior.