Help identifying old keyboard with possible Hall effect switches?

[kirkunit]

So I found this keyboard at an estate sale where I also was able to score some z80/S-100 bus single board computer kit components. Most of everything seemed to be from the early 80s and the person who lived there had clearly been a computer hobbyist. Here are some pictures of it https://imgur.com/gallery/AjCnJie. I've been trying to look up this keyboard on the deskthority wiki and with google searches to try and figure out exactly where it may have come from and what switches it uses, but can't seem to find this model specifically. It looks to me as though it was pulled from some kind of terminal, and it seems as though the SD series of Micro Switch keyboards often used Hall effect switches? Also the date code sticker area is weirdly blank, but might that one other sticker indicate production in the 38th week of 1979? I'm not super knowledgeable about keyboard switches outside from the common cherry/alps/buckling spring stuff, so I was hoping somebody here might be able to identify what these are based on the pictures. The keystrokes are incredibly smooth and light, a very interesting feel. Would that cable be using a 25-pin serial connection? How difficult would it be to adapt this to use on an old DOS system? The keyboard is in immaculate condition and I really like the keycaps, but this is a bit outside of my comfort zone relative to what I typically use and collect so I might just sell it so that it can get in the hands of someone who could really use it.

[Muirium]

A little search found this video with the same Micro Switch model number: 78sd11-2. Ten minutes in:

Actually, the fella has a sequence of 3 similar but distinct Micro Switch keyboards in this video. Check the two straight after. They made a lot of variations on a theme.

I have one of these Honeywells too. Still meaning to convert it to USB, or Bluetooth for that matter! I believe people have made some progress with them over recent years.

By the way, these boards are certainly not PC compatible. The connector is a custom thing, dating before the IBM PC. Don’t hook it up! It needs some work.