The simplest possible shift register is one that uses only flip-flops, as shown in Fig. 6-3. The
output of a given flip-flop is connected to the D input of the flip-flop at its right. Each clock
pulse shifts the contents of the register one bit position to the right. The serial input Mrmines
what goes into the leftmost flip-flop during the shift. The serial output is taken from the output
of the rightmost flip-flop. Sometimes it is necessary to control the shift so thatitoccurs only
with certain pulses, but not with others. This can be done by inhibiting the clock ftom the input