Re: Z80 Serial Port Plug in Board
> I remember in some magazine back then a board that you could plug into a Z80 CPU socket via ribbon cable and it would add a serial port to your computer.I don't recall ever seeing such things, else the ZX80/Timex-Sinclair 1000 folks would've jumped at the chance. The only piggyback device I recall is the GIDE (adds ATAPI/IDE disk controller).
There are so many UART chips (as well as the Zilog SIO and DART Z80 interfaced UARTS) that it's hard to guess what was used. Unless it was polled (which severely limits the throughput), using interrupts is hard since the Z80 could be using any of the interrupt modes.