Historical note: At least one real machine actually had a grind crank -- the R1, a research machine built toward the end of the days of the great vacuum tube computers, in 1959. R1 (also known as `The Rice Institute Computer' (TRIC) and later as `The Rice University Computer' (TRUC)) had a single-step/free-run switch for use when debugging programs. Since single-stepping through a large program was rather tedious, there was also a crank with a cam and gear arrangement that repeatedly pushed the single-step button. This allowed one to `crank' through a lot of code, then slow down to single-step for a bit when you got near the code of interest, poke at some registers using the console typewriter, and then keep on cranking.