Operator control panel
Provided by the ASK Keyboard Dictionary
An operator control panel is a component found on some console keyboards that hosts buttons and lights for low-level CPU operations. OCPs were typically black and originated from the much larger control panels found on the front of IBM mainframe (System/360 and System/370) processing units. When IBM adopted CRT-based operator consoles, this panel became smaller and integrated on the top of various IBM keyboards (mostly from the Model B keyboard family). An OCP may have buttons for IML or IMPL (initial microcode/microprogram load), Lamp Test (to test the lights on the OCP or other I/O devices), Power On/Power Off, and various other host-specific features. Some may even have an emergency pull that when pulled will cut power to the host CPU and has to be mechanically reset.
