A plug-board, or, more formally, a control panel was a device used to program unit record equipment (and some early computers) built by IBM and other companies from 1906 to the 1960s. Removable plug-boards were introduced with the IBM type 3-S tabulator in the 1920s. Each machine type had its own plug-board configuration, customized to its design and, usually, any available options. Each board was roughly one to two feet on a side and had a rectangular array of holes. Plugs inserted into pairs of holes made connections between pairs of contacts on the machine when the board was snapped into place. For example, the output of a card reading brush might be connected to a punch solenoid in a card duplicator. It was a relatively simple matter to copy some fields, perhaps to a different location, and ignore others by suitable wiring. More complex applications involved wiring up counters and relays. Multiple board would be kept for different applications. One board might be used for the weekly payroll, another for monthly reports, for example. Programming required a knowledge of the operation and timing of each machine type.

External link

• http://www.columbia.edu/acis/history/plugboard.html

History of computing | IBM hardware