We will refer to the present state as q and the next state as q★. (Some
books use Q or q or q(t ) to represent the next state.) The next state
is what will be stored in memory after this clock transition. That will
then become the present state at the next clock time. The next state is a
function of the present state and the input, x. The output, in this example,
depends on the present state, but not the present input. The output only
changes when the state changes, at the time of a clock transition. The
first row of the table signifies that if the system is in state A, that is, fact
A is stored in memory and the input is a 0, then the next state is A (that
is, A is to be stored in memory again); and if fact A is stored in memory
and the input is a 1, then the next state is B. Whenever the system is in
state A (or B or C), the output is 0.