PDP-9 DM09A Adapter/Multiplexer

This document is the maintenance manual for the DM09A Adapter/Multiplexer, an option for the Digital Equipment Corporation PDP-9 computer. The DM09A serves as an interface, allowing up to three I/O devices to access the PDP-9 memory via the Direct Memory Access (DMA) channel.

The manual covers:

• Introduction: Explains the DM09A's function and provides related documentation references for the PDP-9 system and Digital's logic handbook.
• Specifications: Details environmental compatibility (same as PDP-9), power requirements (from PDP-9), physical dimensions (two mounting panels), lack of external controls/indicators, and performance characteristics (1 µs/transfer for high speed, 3 µs/transfer for low speed I/O, though PDP-9 DMA and memory only require 1 µs).
• Installation: Provides instructions for installing the modules into preassigned locations within the PDP-9 cabinet, along with interface drawing references.
• Principles of Operation: Offers a detailed explanation of the DM09A's logic, including power turn-on, internal control pulse train generation, and specific descriptions of three transfer types: Single-Fast-Input, Single-Slow-Output, and Double (Back to Back)-Fast-Output cycles. This section heavily references engineering drawings for timing and signal flow.
• Acceptance Test Procedure: Outlines the testing process using "Test Procedure DM09A-0" under normal and specified voltage margin conditions.
• Maintenance: Refers to general PDP-9 maintenance procedures, covers delay adjustments, and lists the required module complement for the DM09A option.
• Engineering Drawings: A list of all associated engineering drawings for the DM09A.