The Omnibus Interface

This document, Chapter 9 of the PDP-8/E manual, outlines the functionality, structure, and design requirements of the OMNIBUS interface. It explains how all modules, including options, connect to the OMNIBUS, effectively eliminating backplane wiring and allowing for high-density, reliable electronic packaging. The text provides guidance for designers on building custom interface modules, detailing the bus signal assignments, electrical specifications, and logic levels. It also covers system expansion options, the relationship between the External Bus and the OMNIBUS, and includes comprehensive tables and diagrams for signal functions, bus loads, and pin assignments to assist with custom hardware integration.