Programmed Data Processor-6 Handbook

This handbook describes the Digital Equipment Corporation PDP-6, a general-purpose digital computing system designed for scientific data processing. Emphasizing flexibility and modularity, the PDP-6 allows users to customize its data handling capacity and configuration, supporting expansion with both existing and future equipment. It operates asynchronously, facilitating memory modules of varying speeds and multiple processors sharing memory.

The system is structured around two primary busses: a processor-memory bus, enabling direct addressing of up to 262,144 words of core memory with automatic overlapping and simplified multiprocessor operations, and a processor-input/output bus, capable of servicing up to 128 devices via a seven-channel priority interrupt system. Key processors include the 36-bit Type 166 arithmetic processor, featuring 16 accumulators, 15 index registers, floating-point arithmetic, byte operations, memory protection, and relocation registers for time-sharing. The Type 167 I/O processor offers direct memory access for high-speed devices, allowing parallel I/O and arithmetic processing.

Memory configurations are modular, including Type 163 Core Memory (8,192 or 16,384 words) and Type 162 Fast Memory (16 words, 0.4 microseconds cycle time), with options for memory overlapping and protection in multi-user environments. The programming system comprises a supervisory control program for overall coordination, a suite of system programs (e.g., FORTRAN II compiler, MACRO6 assembler, editor, debugging aids), and a library of utility subroutines. The instruction set includes categories for data transmission, arithmetic and logical operations, executive functions, and push-down instructions. A wide range of input/output equipment, from tape and card readers/punches to teleprinters, line printers, CRT displays, magnetic tape systems, and data communication systems, is detailed, none of which requires special environmental conditions.