Chicken first, or egg: co-development of a legacy OS

A technical advantage from the DEC world places VMS as the first operating system designed before the chipset that it ran upon. MPE’s earliest designs were just as innovative. Stan Sieler, founder and technical lead for Allegro Consultants, and an engineer who worked inside HP’s labs, shared the HP 3000’s history of co-development alongside the seasons of MPE.

By Stan Sieler

I assume that the 16-bit Classic instruction set architecture and the original MPE were designed at about the same time. The architecture was mostly ready/running (real or simulated/emulated) before the software was ready. Once MPE was up and running, some years later there were arguably one to three architectures designed for it (exclusively or not).


A group of about 12 of us (labs, chip people, me for the OS lab) designed a 32-bit architecture for the next generation HP 3000.

The architecture was an evolution of an earlier FOCUS used by Ft. Collins for some HP 9000s (after the 68000 models, before the PA-RISC models), and it (the earlier) was either used by the Amigo (HP 300) and/or was inspired by the Classic 3000 architecture. The project got dropped in favor of the VISION architecture.


This was the object-oriented architecture (with 64-bit virtual addressing) that was going to be the next-gen HP 3000. It would be running what was going to be called HPE. We had HP 3000/4x computers with rewritten firmware emulating it. A couple of hand-made real CPU boards were starting to run when I left HP in September 1983 to start Allegro.

At that time, I had a crude command interpreter running on it under my process management code. I was in charge of process management. VISION was very very interesting.  If I had access rights to an object (say, a record from an IMAGE database with an employee name, a date-of-hire, and other information), I could send another process a “descriptor” (virtual address) that would give them access to precisely the subset I wished (e.g., read access to date-of-hire field of the record). But, that concept is gone now.  No one can do that.

Vision was dropped in favor of PA-RISC about a month or so after I left. I commented to Joel Birnbaum that it was dropped because I’d left HP. His reply was, “If I knew that, I’d have gotten rid of you sooner.”

About 1982-1983 I began to hear about an architecture that HP Labs was working on that would allow you to run MPE, RTE, and maybe even HP-UX simultaneously.  It was code-named “Rainbow.” I think Rainbow turned out to be PA-RISC.


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