Counters and Registers
453
Figure 11.39 Timing waveforms of IC 74164.
11.12.4 Parallel-In Parallel-Out Shift Register
The hardware of a parallel-in parallel-out shift register is similar to that of a parallel-in serial-out
shift register. If in a parallel-in serial-out shift register the outputs of different flip-flops are brought
out, it becomes a parallel-in parallel-out shift register. In fact, the logic diagram of a parallel-in
parallel-out shift register is similar to that of a parallel-in serial-out shift register. As an example, IC
74199 is an eight-bit parallel-in parallel-out shift register. Figure 11.42 shows its logic diagram. We
can see that the logic diagram of IC 74199 is similar to that of IC 74166 mentioned in the previous
section, except that in the case of the former the flip-flop outputs have been brought out on the IC
terminals.