In the preceding diagram, the truth table represents the switching network and lists all
possible combinations of switches A and B. An open switch is represented by a 0; a
closed switch, by a 1; therefore, their truth values are either 0 or 1. The truth table shows
that both switches must be closed (1) before the lamp will light. The Boolean expression
for this condition is AB (read A and B). A truth table is a chart of a logic function which
lists all possible combinations of
values and indicates the
value for each input combination.
In Boolean algebra, the two possible values for any variable are
a. yes and no.
b. 10 and 01.
c. true and false.
d. 0 and 1.
It is possible to construct a truth table for a logic diagram containing any number of
inputs. The simplest way to determine the number of possible input combinations is to
use the number of inputs as an exponent of the number 2. For example, a truth table for a
two-input logic diagram has 22 = 4 possible combinations of inputs; a three-input logic