Unicomp RP2040/Pico Model M controller purchasing & flashing Vial-QMK guide

Unicomp, the ‘stewards’ of the Model M keyboard family, was forced to update its controller design this year since their previous chip of choice for USB keyboards has been discontinued and [largely] unavailable. This chip was also difficult for anyone to reprogram existing Unicomp Model Ms. With its new controller designs, Unicomp has elected to embrace an RP2040 future, which has opened up opportunities to easily reprogram new Unicomp keyboards!


I’ve written a guide to cover what to know about the controllers and what we can now do with them! This includes some background, how to check if your existing Unicomp keyboard is compatible with them, how to get them for your existing Unicomp, and some basic Vial-QMK download and flashing steps. I’ve aimed this guide mostly towards first-time buyers looking to get more out of their new Unicomp keyboard, but there may be helpful info for others too.

The guide:

The new controller cards are “Justify/Mike Smith” (top) for the Mini M and “Aristides” (bottom) for most of their other keyboards. In keeping with Unicomp’s previous naming convention, they’re named after various parts of Kentucky’s racehorse legacy. They replace the Cypress based “AP1” and “Ruffian” controller cards respectively.

purdeaandrei has now ported Vial-QMK to these new cards as previously alluded to by apastuszak. The two flavours are:

If there’s any suggestions on how to further improve this guide, please let me know!



Based on comments and feedback on my Discord and Deskthority, I’ve overhauled the guide. Changes (which are signposted by clicking the “Show Updates”/“+” button):

  • “How to get them” section has been split so it’s no longer a massive text wall. Two “Compatibility with…” sections and the “Can I make my incompatible keyboard compatible?” section were formed from it.

  • Created “How do I find out if new Unicomp already has one?” section to explain how you can find out what controller your new Unicomp has without opening it.

  • Created “How to fit them” section to explain what, in my opinion, is the best way to fit both the new controllers to their keyboards. This was in response to concerns that the Aristides (101-122 key controller) is too thick to fit existing Unicomp keyboards.

  • Updated info in “How to get them” with the latest info on whether Mini Ms ship with the new controller internationally, and made some changes to the ordering instructions.

  • Updated info in “Can I make my incompatible keyboard compatible?” section reflecting deskthority user jsheradin’s experience with modifying a 1996 Lexmark-made Model M to fit Aristides.


Just want to say, crazy how the knowledge that one of my favorite boards is now using one of my favorite controllers managed to evade me for so long until the article popped into my chrome feed. I might have to consider picking one up to tinker with KMK or my own CirPy build for it.