What's the mechanical switch one? It doesn't look like any Cherry, Topre, or Alps switches I've seen. The spring is horizontal, the actual switch is photo-optical and it seems like it's actuated by an angled part on the key/slider.
https://www.google.com/patents/US4479111
DSB1234567890yeah, I'm wondering the same thing, why I came to the comments here. It kinda looked like a alps, but the stem was what would go into the key cap, opposite of what it should look like.
DSB1234567890It's an opto-electric switch, it's completely different from any other switch and they're extremely hard to come by nowadays; they were developed by Burroughs in like 1982.
https://www.google.com/patents/US4479111