PDP-14

This manual describes the PDP-14 Industrial Control System, a solid-state, modular controller designed by Digital Equipment Corporation (DEC) to replace conventional relay-based systems in industrial binary control applications. It details the system's architecture, programming, installation, and maintenance.

The PDP-14 system comprises a Control Unit (CU), Input (I) Boxes, Output (O) Boxes, and Auxiliary (A/S) Boxes for timers and retentive memories. The CU executes control logic stored in a Read-Only Memory (ROM), which uses a "braid" of wires representing permanent instructions. Inputs (like limit switches and pushbuttons) and outputs (like solenoids and motor contactors) operate in binary (ON/OFF) states, and the system uses Boolean logic to determine output actions based on input conditions, leveraging a "TEST Flag" for intermediate results.

Programming for the PDP-14 is facilitated by three primary software tools that run on a PDP-8 family computer:

• BOOL-14: A compiler that translates Boolean equations into PDP-14 machine code.
• PAL-14: A symbolic program assembler for more direct instruction-level programming.
• SIM-14: A debugging aid that simulates PDP-14 operation in local (offline) or on-line modes, allowing for program testing, equation verification, and truth table generation. An Editor program is also used for source program preparation.

The system is designed for high reliability, maintainability, and versatility, with features like modular components, automated diagnostics, and the ability to redefine control operations by changing the ROM's "braid." Installation guidelines emphasize protection against electrical noise, proper heat dissipation, and careful cabling within a NEMA 12 enclosure. The manual also covers maintenance procedures, including diagnosing faults and modifying ROM instructions manually for minor changes or by generating a new ROM braid for major revisions. The PDP-14 can operate independently or be monitored/controlled by an external computer via an interface, providing status reports and enabling supervisory decision-making.