Logic circuits

Which correctly lists the inputs of a full adder?

  1. AThe two bits to be added and the carry from the lower digit
  2. BOnly the two bits to be added
  3. COnly a clock signal
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Answer: A. The two bits to be added and the carry from the lower digit

A full adder takes the two bits A and B to be added plus a carry from the lower digit, and outputs the sum and a carry to the upper digit. Chaining as many full adders as there are bits forms a multi-bit adder (ripple-carry adder).

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