This reminds me of an old magazine article (Acorn User?) that described how to use a pair of BBC Micros with wired in LDRs and flashlights to transmit data wirelessly.
And that reminded me of a childhood project where I hooked the user port (8 bit parallel) of one BBC up to another and wrote a chat program that sent data from one machine to another by POKEing ASCII values IIRC. Not a million miles from what you could do with an IBM PC printer port.
Not much use, the cable was about a foot long.
My child's generation won't be able to do that, but I'm glad we have arduinos and ESP32s to fill the same niche.
