A simple shift register is shown in figure 7.28. A register of this type can move 3-bit parallel data words to a serial-bit stream. It could also receive a 3-bit serial-bit stream and save it for parallel use.
Figure 7.28: A 3-bit shift register constructed with D flip-flops.
If A is connected back to D the device is known as a circular shift register or ring counter. A circular shift register can be preloaded with a number and then used to provide a repeated pattern at Q.