During the development of my PDP‑11/Hack system I came up with the idea of a generalized interface between the Q-Bus and a microcontroller in order to be able to use the variety of the IO features and the flexibility of the software in a microcontroller. There have been several versions of the Q-Bridge but the basics are all the same. Later I used this concept to port the RLV12 controller of my System to a real Q-Bus PDP-11 System.
A detailed description of the concept of the Q-Bridge. It is a deep dive into the CPLD logic and the Microcontroller software and describes the mechanism behind the logic and the microcontroller interface