Model 8 Add-On Core Memory Technical Manual (PDP 8/I and PDP 12)

This document is a technical manual for the Fabri-Tek Model 8/I Add-On Memory System, designed for use with Digital Equipment Corporation PDP-8/I and PDP-12 computers. The system provides an additional 24K (24,576) words of memory using a three-wire, 3D, coincident-current core memory architecture.

Key sections of the manual include:

• General Information and Specifications: Provides an overview of the system, including its composition (memory unit, multiplexer, and cable assembly), capacity, and operational parameters (split cycle/read-modify-write mode).
• Installation Procedures: Details necessary CPU modifications and assembly instructions for integrating the memory system with the host computer.
• Principles of Operation: Explains the functional components, including the multiplex assembly (which converts the 36-bit memory architecture to 12-bit word processing for the CPU) and the memory unit itself. It covers control signals, data paths, and core array operations.
• Maintenance: Offers a guide to troubleshooting, including recommended test equipment, error classifications (Control, Address, and Data oriented), and specific diagnostic test patterns.
• Replacement Parts List: Provides detailed tables of electronic components (capacitors, resistors, transistors, ICs) for the Memory Assembly, Timing and Control Module, and Multiplexer.
• Reference Documents: A section listing relevant schematics and assembly drawings.
• Appendix A: An alphabetical listing of memory system mnemonics used throughout the documentation.