Model M122 USB-C Conversion Guide Thing

[Seirin-Blu]

This is essentially a copy-paste from the reddit post I made.

Here is the process of me converting my model M122 terminal keyboard to usb C! This mod is entirely non-destructive and completely reversible.

We start out with the Model M122 in the box it came in. This originally was a terminal keyboard so it has a RJ45 jack on the end of its cable and was "hardwired" into the case.


Top of the shell off. Lots of dust, but nothing absurd


Very surprisingly, no rivets gone from the bottom.


Pro micro (elite C) in its little adapter holder (will link below)


Test wiring the Elite C with jumper cables. Everything worked!


My super jank way of keeping all of the wires in the right order. The extra pin is either alignment or extra ground and it works fine without it. Pretty sure going from the bottom left here its yellow, white, red, and then black on top.


Everything all wired up and slotted into place. Yes I plan to open this up in the future and hot glue this so it sticks better. Note the holes the wires are soldered into. This is where you stick them if you do this.


All functional parts back together. This IBM Model M122 is working with an iPad from 2020!


Top view of the port when the case is closed.


Final glamor shot.


Thanks for taking a look at this guide!
Here's the link to models I used for the USB C adapters

[jsheradin]

I love the converging ideas with these mounts!

That modular cable retainer really makes modernizing these boards seamless.

[Seirin-Blu]

I love the converging ideas with these mounts!

I wish I could say I designed this. Someone on Reddit who has better measuring skills than I did so. He’s linked in the GitHub link. But yeah the adapter is nice. I might eventually put a nice!nano inside of it for Bluetooth but I’d have to use zmk which I don’t think works with soarers converter.

[jsheradin]

I might eventually put a nice!nano inside of it for Bluetooth but I’d have to use zmk which I don’t think works with soarers converter.

Indeed it doesn't run Soarer's. Even if you were to implement scan set 3 protocol in ZMK you'd run into the issue of the model M controller needing 5V to run; the nice!nano runs at a mere 3.3V. The stock controller also draws a couple hundred mA so it would drain batteries like crazy. You'd be best off just running the matrix directly off the nice!nano and ditching the stock controller completely.