Can I mod my Unicomp PC122 to output a unique scancode for each key?


12 Jan 2021, 23:34

I have this Unicomp PC122 (UB40B5A): I got it last year around the start of my personal keyboard hobby renaissance. The "works out of the box with USB" was a big selling point for me then, and I didn't really understand how the limitations of the built in layout would affect me.
The Issue
I've set up an AutoHotKey script to convert it to a standard-ish ISO layout. It mostly works, but still has some annoying quirks. For example, Ctrl+Alt+Delete doesn't really work because I have to send this AHK code

Code: Select all

<^F6::Send, {Blind}{Ctrl up}{Delete}
to have delete in the standard place, but because I have to send Ctrl up, Ctrl+Alt+Delete doesn't work. Additionally, getting my remapped keys to play nicely with the various remote connection setups I do for my work is... hit and miss.

So at this point, the PC122 is just my weekend board because it's too annoying to use for work with all the limitations. If I knew then what I knew now, I'd have just ordered it with the layout I wanted from the factory, but I didn't know you could do that, and I didn't even know what I would've wanted the keys to do anyway at that time.

Short of having the built in layout that I want, I'd like to at least output a unique scancode for each key, which would be much cleaner to remap and I could use something like Hasu's USB to USB converter on it.

The closest I've found is this thread viewtopic.php?f=2&t=22168. However, when I opened mine up, I discovered that mine has a different PCB:

I might be able to send it back to Unicomp, but I'd like to explore other options before I pay half the price of the board over again in shipping and customization fees just to get a different layout.

Is there any way to modify my PC122 to output unique scancodes for each key? Is anyone familiar with the PCB in mine that could offer some guidance before I go bricking my keyboard by connecting jumpers I shouldn't?


15 Jan 2021, 15:36

Hi there!

From what I've read, it was precisely this issue which caused me to purchase second-hand 122-key terminal keybaords and add Soarer's Converters, as that will do what you require. The Soarer software will allow you to modify in almost any way the HID codes that an original 5250 keyboardsends - but not a PC122.

Wait - I said "almost"! The Model-M keyboard family doesn't alloww NKRO, so you can't create *any* multiple key combination, which means that you will struggle to go too far creating additional modifier keys, but I have a Windows and Menu key defined as my lowest two keys on the 10-key pad on the left. You mileage may vary!

Your PC122 keyboard essentially looks like a 5250 keyboard, but it isn't wired as such, and as you've discovered, those additional function keys are simply returning modified existing keys. It's a regular PC keyboard that's been hampered with a 5250 layout, and is doing its best to return PC keyboard codes. It's a curious mix of fish and fowl, and for my part, I can't imagine it being of any use to anyone, I'm sorry to say

I don't know about sending the keyboad back to Unicomp, and looking at their website, I don't think they sell 5250 terminal keyboards - or I'd have bought a brand new one myself!

If I were in your position, I'd probably try to sell the PC122 on eBay with no returns, and see if you can acquire a decent pre-cherished authentic 5250 and a Soarer's.

Hope this helps!

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15 Jan 2021, 17:55

I've seen you've already got your answer on your r/ModelM post. Unicomp can produce a controller with single usage code firmware that would be suitable for easy remapping. So as an FYI to anyone thinking about buying a PC-122 for PC usage, might want to drop them an email before your purchase requesting such a controller.
RetroGuy wrote:
15 Jan 2021, 15:36
I don't know about sending the keyboad back to Unicomp, and looking at their website, I don't think they sell 5250 terminal keyboards - or I'd have bought a brand new one myself!
I believe it's under their custom keyboard page, assumingly the non-emulator/non-PC-122 variety.


15 Jan 2021, 21:31

Ah yes, I forgot to update this thread as well!

For posterity, here's what I got from Unicomp:
Unfortunately, there is no way to reprogram the keyboard besides purchasing an alternate logic card and installing it yourself.

We do offer a Single Usage Code firmware for the PC122, which may be purchased by adding 3x customization fees to your cart here: and write in the text field, "Replacement logic card for UB40B5A loaded with Single Usage Code firmware."
It's looking like that's my only option. I'll have to debate selling and buying an older m122 or getting the upgraded firmware.

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