This is part of the "counter and register notes" web pages, which contain the following subtopics:
  1. Ripple counter
  2. Synchronous counter
  3. Synchronous counter with reset
  4. Very simple register (parallel load)
  5. Very simple shift register (serial load)    <-- you are here
  6. Designing a circuit which can shift or load
  7. More realistic shift register with parallel load

Simple shift register

Here we load the register one bit at a time; the SHIFT control line moves everything to the left by one bit, losing the former top bit, and gaining a new low bit.

However, we want to be able to do the straightforward "parallel load" to load completely new contents into a register in one cycle, rather than 32 cycles for a 32-bit register. But the SHIFT facility is also useful. For example, it constitutes multiplying by two.

So we often design a circuit which can shift or load, next.

This is part of the "counter and register notes" web pages, which contain the following subtopics:

  1. Ripple counter
  2. Synchronous counter
  3. Synchronous counter with reset
  4. Very simple register (parallel load)
  5. Very simple shift register (serial load)    <-- you are here
  6. Designing a circuit which can shift or load
  7. More realistic shift register with parallel load

[list of course notes topics available] [main course page]