2 ms·

That is very cool and I say that as someone whose first project in my first job (1982) was to write the code for a serial multiplexer with a Z80, a 2716 EPROM,

That is very cool and I say that as someone whose first project in my first job (1982) was to write the code for a serial multiplexer with a Z80, a 2716 EPROM, Zilog SIOs (or maybe DUARTs actually).... and 2K of static RAM. I basically learned my craft on the job and there's no way I could have done it without the RAM. A few years later I would have relished the challenge. Although you are really limiting the complexity of the protocol you can deal with ... (perhaps not such a terrible thing:).

ChrisMarshallNY 3y ago
Writing code for the old Mac serial chip was an adventure. I wrote a MIDI driver once, and that required dividing a 1MHz external clock, to get the 62.5KHz (I think) serial clock (you couldn’t divide the internal clock). Their chip had 8 control lines, with each line controlling some aspect of the chip operation. They set it up as the lower 8 bits of the 16-bit address bus, with the upper 8 bits fixed (so you were working with 256 addresses, to control the chip). So just referencing an address would change the state of the chip. A lot of hardware limitations influenced software structure, and I’ll bet that a lot of software proclivities have their genesis in weird hardware compromises (like bytes).