Reply #52: Well, I used CP/M inside and out. [View All]

[TahitiNut]

Yep ... Z80 days. Xerox 820. As a Xeroid, I had complete source and docs on every bit/byte. With my handy-dandy M80 Macro Assembler, I drove that sucker to the max, including various emulators I wrote. With the SIO and PIO, I was able to make that little beast behave like a variety of specialized equipment at the end of a serial or parallel interface based on the design specs of that equipment prior to it actually being in production. Those were the days! One of the more interesting projects was to interface like an IBM serial terminal for some application-specific front-ends. I think I had my most fun writing comm software for it.

That was the first (and last) computer that I was able to know from end to end, comprehensively. From that perspective, it was just right.