Around 1980 I built a computer with a keyboard I bought surplus from jameco (before there was jameco.com, I had to mail order out of an ad in Byte magazine:). I don't remember who made the switches (maybe Rockwell? Somebody space shuttle related). They're definitely not the same as in your picture. But they were four pin: +5, Ground, Scan, Out. The scan/out are there to emulate a traditional switch matrix: the conroller still needs to scan columns of switches, and look at the outputs. The difference being that these aren't dumb switches making contacts: the "scan" was a TTL-level input, the Out was an open-collector TTL-level output.
Expensive switches: I wanted to get a couple more to fill some open places in the plate, and the distributor quoted me $17 each in qty 10. And that was in 1980 dollars. I so wish I kept the keyboard. It's probably in a landfill now, I don't even remember.
Anyhow, these may be something similar: internal logic so that they have a digital interface. Or they may just be a power/ground/collector/emitter. You either need to get a spec sheet, or plan to burn a few up while you experiment with them.
