@adamd Oh, this is a very simple PS2 keyboard converter to a dull switchboard. It imitates 7x10 key matrix with dozen special switches and polling which is the task of some ancient controller, similar to teletype😉
I quickly ran out of the processor outputs, but fortunately 74hc595 and optocouplers were close at hand (74hc595 has something about 7mA per pin so optocouplers).
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko