UDSYS a microcode development system

Abstract

This paper describes a microcode development system called UDSYS that is currently in use at Data General Corporation across several radically different micro-architectures. The system was developed to overcome some of the deficiencies of meta-assemblers, namely, one-to-one meaning of symbols vs. action, lack of rigorous syntax verification, and lack of application specific error messages. The system is explained by way of a specific example about the sequencer portion of a hypothetical microword. Microcoding is slowly loosing its status as an artform. Many of the tools available for increasing the productivity of software engineers are now starting to become available for the generation of microcode. There is work being done on machine independent microcoding languages, microcode generators, and microcode optimizers to name but a few such tools. However, many of these tools are still in the developmental stages. At Data General, our current microcode production system took the approach of leaving the optimization in the hands of the coder, but giving him the capability of building a very friendly interface to the hardware. The system is called UDSYS and this paper presents an overview of some of its major concepts and features.