From 1986 to 1989, I worked in the Xenix¹ group at Microsoft. It was my first job out of school, and I was the most junior person on the team. I was hopelessly naive, inexperienced, generally clueless, and borderline incompetent, but my coworkers were kind, supportive and enormously forgiving – just a lovely bunch of folks.

The story of the Commodore SuperPET has always been something of a mystery to me.

The SuperPET was the last of the original PET computers, but was oddly unrelated to its siblings; it featured hardware and software that were radically different from every other machine in the series.

Commodore’s key manufacturing strength was vertical integration – they even went so far as to design and build their own semiconductors – but the SuperPET prominently featured a competitor’s microprocessor.

Somehow, just as Commodore was making a strategic move away from building high-end machines to focus on low-end computers like the VIC-20, they produced the most expensive and complex PET ever.

Stranger still, the key software for the SuperPET came from an academic software team at the University of Waterloo, and much of the hardware design seems to have been Waterloo’s as well.

How did a group at a small university in Canada end up designing their own microcomputer, and how did they convince one of the largest personal computer manufacturers in the world to build and market it?

How did the SuperPET come to be?

Prehistory

October, 1977

After initially announcing it some 8 months earlier, Commodore International ships their first computer, the PET 2001. The 8k version sells for $795.

December, 1978

After a year, Commodore has sold approximately 4000 PETs in North America. At this point, the PET is the most successful of the initial wave of mass-market personal computers (Apple, Tandy, Commodore), both in terms of number of units sold and in overall revenue.¹

The HOSTCM protocol is a mechanism that allows a Commodore SuperPET or IBM PC running the Waterloo microSystem kernel to communicate with a remote file server over a serial line. This is a brief overview of the internals of the protocol.