Idea of master/slave serial comm.

[Ioannis]

How do you think the Z80 & 8086 controllers managed to do stuff like this? (All software-based)

Didn't they rely on external chips for USARTS, PIO, RTC etc?

I still remember the 8251 (UART), 8253 (Counter-Timer) and 8255 (PIO) chips! Good old times!

Ioannis