Microware Systems Corporation--it was fun to work with really good people on compilers for an operating system that, at the time, was one of very few pre-emptiv

Microware Systems Corporation--it was fun to work with really good people on compilers for an operating system that, at the time, was one of very few pre-emptive multitasking OSs one could get for relatively inexpensive computers. It didn't require memory mapping hardware, and thus couldn't use compilers that presumed knowledge of some absolute address where code and data lived (or could be made to appear at with memory mapping). Probably the most fun was modifying the compiler to take advantage of the "as if" rule by avoiding the "usual arithmetic conversions" where possible. I kick myself periodically for not trying to get that published.