I recently picked up this weird board from eBay. The seller says it was "salvaged industrial control equipment", and like the seller I also couldn't find any other information about the board or even the company that made it. It comes with KeyTronic magnetic reed switches, which I wasn't expecting. All of the switches except for the TTY lock switch are identical, and they are not either of the variants reported in the wiki article. They are arranged in blocks of size 1,3,4,5, or 6. The majority of the sliders have a raised circle on the top that is placed off center that indicates where the top of the slider is. The TTY lock switch has a light instead of the plastic peg that the other switches have, and the reed is located outside the slider. The slider has no top on it (to let the light through), and it has a magnet on the outside which presumably activates the reed, and internally it has a plastic ring instead of a magnet. There are four kinds of keycaps, the normal KT ones, the clear top variant on the TTY lock cap that isn't removable, the regular shaped re-legendable caps, and the square shaped re-legendable caps. The board also has a speaker in the back, a 22 foot long massive cable (which is the longest I've ever seen), and also a lock in the top right. Luckily I received the key to the lock, and the lock is connected to the cable which presumably sent information to the system this board connected to. There's also a CPU on light that has a cable that connects to the main cable. Unfortunately I couldn't find a date code anywhere, but from what I researched it might be from the late seventies or early eighties.
TTY Lock light and off center reed