Question 13.5: Design a 16-bit serial-to-parallel converter....

First, we have to look through a TTL data manual to see what is available. The 74164 is an 8-bit serial-in, parallel-out shift register. Let’s cascade two of them together to form a 16-bit register. Figure 13–21 shows that the Q_{7} output is fed into the serial input of the second 8-bit register.
This way, as the data bits are shifted through the register, when they reach Q_{7} the next shift will pass the data into Q_{0} of the second register (via D_{Sa}), making it a 16-bit register. The second serial input (D_{Sb}) of each stage is internally ANDed with the D_{Sa} input so that it serves as an active HIGH enable input.