Prior to moving to PDP-11's and paper-tape, the special-effects company I worked for many years ago used analogue computers stuffed with op-amps to control the

Prior to moving to PDP-11's and paper-tape, the special-effects company I worked for many years ago used analogue computers stuffed with op-amps to control the motion of camera rigs - i.e. analogue motion control. I never saw one in operation, but apparently a cardinal sin was opening the door when the system was in operation (the temperature change would cause enough error to ruin the shot).