PDP-14

The PDP-14 was a specialized computer from Digital Equipment Corporation’s Industrial Products Group designed to replace industrial level relay controls for machinery and machine tools that performed repetitive tasks. It was specifically designed to function in the harsh electrical environment encountered in facilities where electric motors, solenoids and arc welders were present, a significant adversity for normal computer electronics. The PDP-14 was specifically designed to be the first level of factory automation, functioning as a programmable logic controller (PLC), through its ability to communicate with a standard DEC PDP-8 minicomputer.[1][2]

The first unit was delivered in June 1969 and used to control a gear grinding machine.[3] Its design as a "programmable machine controller" was patented in 1973.[4]

The PDP-14 was designed to process Boolean equations, usually expressed as “ladder diagrams” and as such had a programmable read-only program (PROM) memory.  Programs were developed using a PDP-8 then tested using a direct connection to the PDP-14.  The PDP-14 was put into a check out mode where instructions were provided by the PDP-8. Following checkout, the PDP-8 provided the instructions to be put into the PROM.

Later versions (for example, the PDP-14/30, whose instruction set was not binary compatible)[5] are based on PDP-8 physical packaging technology. There also was a PDP-14/35[6] and a lower cost/reduced I/O capability PDP-14/L.

  1. ^ Bell, C. Gordon; Mudge, J. Craig; McNamara, John E. (2014-05-12). Computer Engineering: A DEC View of Hardware Systems Design. Digital Press. ISBN 978-1-4832-2110-6.
  2. ^ PDP 8/e, PDP 8/m & PDP 8/f Small Computer Handbook (PDF). Digital Equipment Corporation. 1973. p. 1-46.
  3. ^ Ball, Ken (2015-08-02). "The Dawn of the Programmable Logic Controller (PLC)". automation.com. Retrieved 2024-03-02.
  4. ^ US3753243A, Ricketts, A.; Devault, A. & Doane, R. et al., "Programmable machine controller", issued 1973-08-14 
  5. ^ "DEC PDP-14 Industrial Controller".
  6. ^ Nineteen Fifty-Seven To The Present (PDF). Digital Equipment Corporation. 1975.