[kmill]

I am having a very difficult time believing this.

- I cannot find about "diode cascades" having anything to do keyboards. The closest is the usual diode matrix to deal with simultaneous key presses.

- The PS/2 interface involves sending scan codes, parity bits, and start and stop bits. How exactly does a "wave of electricity" get converted into a PS/2 waveform without some digital electronics?

- All the old schematics for mechanical keyboards I could find were the usual matrix scan. Even a textbook from the 1970s.

Anyway, reference please. I'd find it very interesting to see how such a thing would work.