Name/Title
1951- IBM 557 - Plug Board (1/2024)Tags
IBMDescription
1950's- The IBM 557 Alphabetic Interpreter (photo) allowed holes in punch cards to be interpreted and the Hollerith punch card characters printed on any row or column, selected by a control panel. The machine was a synchronous system where brushes would glide over a hole in a punch card and contact a brass roller thereby setting up part of a character code. There are no 557's operating commercially in the world today. A plug board, or control panel, was a device used to direct the operation of unit record equipment, some cypher machines, and some early computers. They consisted of a number of plugs, or jacks, into which patch cords were inserted, completing a circuit. Wiring the plugboard "programmed" the system, which operated as a sort of read only memory. Control panels were first introduced 1906 for the Hollerith-tabulated census, earlier machines had been hard wired for specific applications. Removable plugboards were introduced with the Hollerith (IBM) type 3-S tabulator in the 1920s.
