A very important byproduct of the development of SIMPOS was training of logic programming language programmers.
The largest software on PSI was its operating system SIMPOS. It went through many revisions and added more and more functionalities, including debugging and performance-tuning facilities, on ever-increasing users' demands.
Not only the operating system but also other basic software systems were built up on PSI and SIMPOS. A database system Kappa based on a nested relational model was probably the largest such system.
SIMPOS were ported to the machine relatively easily.
When the basic design and the development time table of SIMPOS were more or less established, I could find some time for my participation in the design of CP implementation.
From this stage (i.e., from 1986), I was more fully involved in the parallel systems research as SIMPOS was approaching its maintenance phase.