grind crank: n. A mythical accessory to a terminal.

:grind crank: n. A mythical accessory to a terminal. A crank on the
side of a monitor, which when operated makes a zizzing noise and
causes the computer to run faster. Usually one does not refer to a
grind crank out loud, but merely makes the appropriate gesture and
noise. See {grind} and {wugga wugga}.

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.
-- The AI Hackers Dictionary