Abstract: A rocker type electric switch operated by pressure on a knob which actuates a spring biased plunger that exerts a switch closing force on a movable switch contact element, in combination with means for preventing said plunger from forcing said element to the switch closed position until the knob and plunger have been rotated through a predetermined angle to a preselected position.

Abstract: A device is provided for teaching the operation of an electronic computer. The device includes a mock control panel display having an overall configuration and appearance substantially identical to that of the display of the actual computer. The mock display includes simulated light and control elements of like type and kind to those of the actual computer. A projector is provided, designed to project an image viewable from the front of the mock display thereby causing portions of the mock display to resemble an illuminated light array of the computer display.