I've used it once making a DRAM refresh controller. That was almost forty years ago before DRAMs came with refresh circuitry build in and before you could get d

I've used it once making a DRAM refresh controller. That was almost forty years ago before DRAMs came with refresh circuitry build in and before you could get dedicated chips for it. I made this 6-state sequencer ABC -> A'B'C' 000 -> 100 -> 110 -> 111 -> 011 -> 001 -> 000 -> ... This sequence requires minimal hardware to program A' = not(C) B' = A C' = B Also easy to decode the states for control signals 000 = not(A) & not(C) 100 = A & not(B) 110 = B & not(C) etc. I remember this especially because I made a bug. I forgot false state prevention. If the circuit starts randomly at power up, it may enter this sequence 010 -> 101 -> 010 -> 101 -> 010 -> 101 -> ... and it did at one test.