Page 1089 - Basic Electrical Engineering

For constructing the truth table, we will first write the various combinations
of the inputs at A and B in the form of binary numbers (the total number of

N
possible combinations being Z where N is the number of inputs). We then
calculate Y and Z, and then X is calculated.

Boolean expression for any logic function can be obtained from the truth
table. This is done by taking the sum of all terms which correspond to all

those combinations of inputs for which the output attains a high value. Let us
consider the truth table of the above example.

A B X

0 0 1
0 1 0

1 0 0

1 1 1

The first row and fourth row have to be considered where output is high, i.e.,

1.
Inputs A and B are to be considered 1. The complement and therefore 0.

For row 1