... remains the same. Take for example a three-input AND gate. There are four cases when the input A=0: A=0, B=0, and C=0; A=0, B=0, and C=1; A=0, B=1, and C=0; and A=0, B=1, and C=1. Each of these ... the output of an AND gate that takes as its inputs step (a) and input A. Add another column for step (b) and fill it with the AND of columns A and (a). A B C (a) (b) = (a) AND A0 0 0 1 0 ... being input to the circuit. Figure 4-12 below shows that for a two-input XOR gate, this occurs twice, once for A=0 and B=1 and once for A=1 and B=0. A B X 0 0 0 0 1 1 1 0 1 1 1 0 Figure 4-12...