Beckman 421 Controller (Cherry keyboard with M7 switches)

[afan]

Hey folks, I scored this awesome terminal at flea market the other day and wanted to share some pictures with the community. I'm no expert in keyboards or switches, but after some research it looks like what this keyboard has is Cherry M7 linear switches with doubleshot SA keycaps. All keys have a T stem, except for one "LOCK" key that has a grey "|" stem with a latch mechanism.

Enjoy the photos!

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[afan]

The terminal itself looks like this (this is not my picture, as I currently have it disassembled for restoration):



More pictures here.

[Blaise170]

That's quite the find!

[UncleFan]

I guess the grey switch is the alt.action switch, right?

[afan]

@UncleFan The grey switch is under the "LOCK" key. Since this keyboard made for a very specific use case (for a chromatography lab equipment) it could originally mean anything. This key physically keeps itself in a pressed state, so in my version of keyboard layout I'm using it is a modifier key that can permanently switch keyboard layout to an alternative one (I managed to find out the way its matrix is scanned and created a converter using Arduino Pro Micro + QMK).