Microprogramming the PDP-11s

This document, written by J.F. O'Loughlin, analyzes the application of microprogramming across three PDP-11 models (PDP-11/05, PDP-11/40, and PDP-11/45). It reviews design goals, implementation techniques, and the use of design tools like control stores and simulators. The paper highlights the impact of microprogramming on machine performance, complexity, and expansion capabilities, while also comparing them to the original non-microprogrammed PDP-11/20. The author concludes with a discussion of production considerations, specifically the trade-offs between standardization and customization when using Read-Only Memories (ROM) and Programmable Read-Only Memories (PROM).