What is another name for a serial in/serial out register?

• A. Shift register
• B. Counter
• C. Decoder
• D. Multiplexer

Answer: (A)

A serial in/serial out register is all about moving data one bit at a time through a chain of storage elements on each clock pulse. That behavior is exactly what a shift register does: it shifts bits in from one side and shifts them out from the other, storing them as they pass along. The other devices perform different tasks: a counter increments counts of events, a decoder turns binary input into a specific active line, and a multiplexer selects one of several inputs to feed the output. So the name that best fits a device that accepts bits serially and outputs them serially is a shift register.