BT-USB-Hybrid controllers for Model M 122, M2, Unicomp M

[mind_prepared]

All common variants of the Model M keyboard are now supported (with the exception of the M122 variant manufactured by Unicomp, which is probably very, very rare). That leaves the M2 as the only board I cannot support for now because that would require designing an altogether different controller board, just a daughterboard wouldn't do the trick.

Update - controller board, daughterboard and optional items to be included in a conversion kit:

blusb_controller_rev_2.3_kit_1.jpg (606.35 KiB) Viewed 14741 times

(1) M122 daughterboard, (2) jumper cables to connect daughterboard and main controller board, (3) shield ground wires long and short, (4) HID proxy dongle, (5) USB-B-›USB-A cable, 1.8m, (6) LED daughterboard (JST EH header) and JST EH connector wire 210 mm, (7) controller board

Update 2 - the daughterboard for 4th generation/Lexmark/Unicomp boards:

blusb_unicomp_daughterboard_top.jpg (379.27 KiB) Viewed 14674 times

blusb_unicomp_daughterboard_bottom.jpg (556.99 KiB) Viewed 14674 times

blusb_unicomp_daughterboard_mounting_connections1.jpg (721.01 KiB) Viewed 14674 times

blusb_unicomp_daughterboard_mounting_connections2.jpg (1.22 MiB) Viewed 14674 times

Feel free to ask or suggest anything that's on your mind.

Interest check: Model M2 anyone?

digitalMatthew 1x
...

[mind_prepared]

reserved

[Myoth]

hey, the link broken, please remove the ) from the link

[Arakula]

I'd definitely be interested in at least one M-122 board. As you know, mind_prepared, I got 4 of them by now; all hand-modded to USB with Soarer Converter on a Teensy 2 or Pro Micro, 3 of them with added LEDs in the exact same position as the previous Unicomp PC/122 generation had (i.e., using the original Model M "LEDS on bottom of the overlay" position and spacing). Getting the 30+ year old original controllers out would be a good thing. Nothing lasts forever ... and these controllers will presumably die first, long before the keyboard assembly.

To make things a bit more "fun", I also got a Unicomp PC/122 with a PS/2 connector. When asked whether I could have a replacement controller board for USB, they told me that they switched the board layout after I bought it (and yeah, they did - I also got a new black USB PC/122 for comparison. Totally different, and not for the better) and don't have the older style controller board any more. That is a beast that I'd love to drag out of its box (where it sleeps since I switched my KVM from a PS/2- to a USB-based one) and into the USB/BT era ... AFAIR, it got a rather special controller board (sitting on the right side, including the LEDs). I could take some photos of its innards if you're interested.

[ConiKost]

I would be also interested in at least one M-122 board. Got a couple of M-122 here..

[mind_prepared]

I also got a Unicomp PC/122 with a PS/2 connector. ... That is a beast that I'd love to drag out of its box (...AFAIR, it got a rather special controller board (sitting on the right side, including the LEDs). I could take some photos of its innards if you're interested.

yes, and please provide some dimensions, too. We might as well start thinking about USB micro/mini socket placement. It would have to be attached to the wall of the cover where the cable exits, somehow.

[depletedvespene]

I have to wonder if the different versions of the M122 use the same internal controllers even if they use different connectors and stuff (DIN, RJ45, etc.).

[mind_prepared]

I have to wonder if the different versions of the M122 use the same internal controllers even if they use different connectors and stuff (DIN, RJ45, etc.).

That doesn't matter. The ribbon cables should always be the same, one with 20 and one with 8 traces, which gives a 20x8 matrix.

[InvidiousIgnoramus]

I too have one of those Unicomp PC-122s with a PS/2 cable. If it can be done with that, that would be a yes for me.

[depletedvespene]

Did I say "Me too!"?

[Arakula]

I also got a Unicomp PC/122 with a PS/2 connector. ... That is a beast that I'd love to drag out of its box (...AFAIR, it got a rather special controller board (sitting on the right side, including the LEDs). I could take some photos of its innards if you're interested.

yes, and please provide some dimensions, too. We might as well start thinking about USB micro/mini socket placement. It would have to be attached to the wall of the cover where the cable exits, somehow.

Ooooo-kay ...

I've taken this little fellow apart:

IMG_1607_sm.jpg (150.64 KiB) Viewed 15892 times

The cable is "clamped down" (don't know whether that's the correct English word) with a little plastic part, using the same construction as the normal Model Ms do, so a little board with just the USB port, LEDs, switch, and the two 3.2 mm holes instead of the plastic clamp should work quite nicely.

IMG_1608_sm.jpg (134.99 KiB) Viewed 15892 times

Lifting the lid, we see this:

IMG_1609_sm.jpg (268.48 KiB) Viewed 15892 times

The controller board isn't located on the backside of the metal plate, it's attached to the upper right corner with two screws. This allows to add the usual 3 LEDs, just with a weird little twist: 2 of the LEDs are partially behind the flat cable:

IMG_1610_sm.jpg (234.13 KiB) Viewed 15892 times

... which is a bit weird, but works. The LEDS are placed in irregular distances, but the holes in the cover are in the normal IBM layout (1" spacing). Works OK, but I don't see any reason to keep the asymmetric layout if you really create a replacement.

[Update:] Bottom part of the shell looks like this:

IMG_1612_sm.jpg (151.64 KiB) Viewed 15844 times

and, for good measure, the inside of the right upper part of the shell looks like this:

IMG_1613_sm.jpg (258.4 KiB) Viewed 15844 times

... prepared for both kinds of LED positions.

Here's the front side of the controller board, with the PS/2 cable connector on the left side:

ControllerBoardFront_trans.jpg (1.07 MiB) Viewed 15836 times

And here's the backside of the controller board, with the relevant measurements im mm (as good as I could take them without desoldering anything):

ControllerBoardBackMeasured.jpg (323.36 KiB) Viewed 15892 times

Presumably, the original design was done in a 1/10" grid, so they might be off a little bit.

HTH

[mind_prepared]

@Arakula

hm, interesting. That's 'yet' another type of Model M which would require a special PCB layout. It would be complete overkill to make a special PCB for every kind of Model M out there, I'd rather keep things simple. Is there a way we could unify the design a bit, at least for the M122?

Could a 170x50 mm PCB be mounted inside the bottom cover? I understand that this particular Unicomp M122 has an outlet for an SDL socket, including the 3.2mm mounting pins for the controller PCB, although its controller is placed in a different spot. It would probably be smart to put the replacement controller PCB near the outlet instead of making a daughterboard, but a daugherboard might be used for the LEDs and FFC sockets to connect the ribbon cables. What do you think?
If you don't mind, please add a picture of the bottom cover without the keyboard assembly, just so that I can see where to put what.

[Arakula]

I added pictures of the lower part of the shell and the LED part of the upper part to my post above. At a glance, without taking exact measurements, it looks exactly like the lower part of the shell of "normal" 122-key Model Ms with SDL sockets. So, it should work by "just" adding a matching daughterboard.

Also, please put my name under "2. Unicomp Model M/Model M 4th generation (small controller PCB in the upper right corner, fixed cable)". I got 2 '96 Model Ms and a Unicomp with that layout, all of which would benefit from a replacement controller.

[mind_prepared]

Do you see a way to make a one-size-fits-all controller for these boards?

I've taken a look at the bottom cover of a 'regular' M122 and there's no way the current PCB will fit in there, so a daughterboard is the only way to go (as you suggested). That's probably not so bad design-wise anyway. If I'm gonna make a new controller for the M122, I would want it to be compatible with any M122 out there (if that's possible). My idea is to use the same motherboard for all M122s and just add the necessary daugherboards according to the different variants. One daughterboard will carry the USB socket, charging LED, BT status LED and slide switch and another daughterboard will carry the locking LEDs and (optionally) FFC sockets for the ribbon connectors.

Would it be possible to mount a 'regular' M122 controller inside your Unicomp M122? Does the back plate have the same characteristic pair of embossed mounting holes?

[Arakula]

Would it be possible to mount a 'regular' M122 controller inside your Unicomp M122? Does the back plate have the same characteristic pair of embossed mounting holes?

Unfortunately, no.

IMG_1805_sm.jpg (98.56 KiB) Viewed 15781 times

[mind_prepared]

ok, I see. Apparently the IBM engineers must have been really bent on making like three different versions of that keyboard with different controller layouts and mounting mechanisms for each one. Darn them!

[mind_prepared]

bumpety-bump

[just_add_coffee]

I voted for the M122 and Unicomp.

[mind_prepared]

bumpin the threat again so it won't get lost. However, I've been thinking about the necessary design changes lately. I could probably free up enough MCU pins (the M 122 needs 20 to read the columns, the current design only supports a maximum of 16) by using a 1-wire PWM IC driver for the LEDs. I'll start figuring out how to talk to these ICs with the MCU and, hopefully, there will be a M 122 replacement controller available soon.

[Iggy]

I voted for the M122.

[mind_prepared]

alrighty, I've freed up enough MCU pins for a 20x8 matrix by adding a 1-wire PWM LED driver for the status indicators (even though, by default, the M122 doesn't have LEDs nor pre-drilled holes for an LED overlay), so from a technical perspective, the path is cleared. I think I'm gonna start re-designing the PCB layout to make it a universal fit for 1st-3rd generation 101/102 key Model Ms and what seems to be the most common M122 variant. The PCB will need some cutouts/slots to fit inside the bottom cover of the M122 though because the right-hand side rest for the keyboard assembly is in the way (see 5th image from the top).

Anybody got a good idea how to deal with the fact that there are no cutouts/holes for status indicators in the top cover? Anyone wanna volunteer to make suitable LED overlays for the M122?

Anyway, if you're remotely interested in getting a replacement controller, make sure to leave a message (if you haven't already).

[mind_prepared]

ok, so here's a new prototype. This controller board is truly universal and can be used with any Model M board out there (although some slight modifications and extras might be necessary) (except M2). I've also added new features to the firmware, s.a. support for up to 24 macro keys.

blusb_universal_1.JPG (356.16 KiB) Viewed 15367 times

Just in case anyone's wondering: the FFC sockets have 16 and 8 pins, respectively, and can only be used to connect a 16x8 matrix. To connect an M122's 20x8 matrix a daughterboard is necessary. So the final M122 conversion kit will include a daughterboard featuring a 20 pin and an 8 pin FFC socket plus pin header to connect the main controller board and the daughterboard with multi-wire jumper cables.

Similarly, a daughterboard could be made to connect the matrix on 4th generation boards. And instead of a B-type USB socket, some kind of wall-mount micro- or mini-USB socket could be used. That only leaves the question of how to break out the LEDs and the mode selection switch. Either openings could be drilled/milled or pre-existing openings in the bottom or somewhere else may be used.

If you haven't already, vote and let me know if you would be interested in a replacement controller.

[mind_prepared]

The controller board will fit inside any Model M keyboard. To connect a M122, 4th generation Model M or Unicomp Model M, a daughterboard is necessary, just in case anybody's wondering.

Anyway, here's a few pictures of a converted M122. I hope they also convey the relative ease with which a conversion can be carried out. Although a daugherboard is necessary to connect the matrix, I've designed it such as to create a straight and short path between the pin headers on the daughterboard and the main controller board in order to avoid the hassle of having to route long jumper cables beneath the keyboard assembly.

Since the controller board includes pin headers to connect the matrix now, it could also be used for other keyboards as well (as long as there's enough space for it).

blusb_universal_prototype_(2)_captions.JPG (741.14 KiB) Viewed 15306 times

blusb_universal_prototype_(3).JPG (511.21 KiB) Viewed 15306 times

[Iggy]

Nice, I recently did a bolt-mod on a M122 and this new controller would go great with it.

[Chalba]

M122 plz!

[mind_prepared]

hey guys, I'm making a new batch right now (12 PCBs), mainly for the people who've pre-ordered a M101/102 controller board (see other thread) and have been waiting for forever, and for the people who've signaled their interest in a replacement controller for their M122. Let me know if anyone else would be interested.

[digital_matthew]

I voted for the M2. Those PCBs always need their capacitors replaced, and that is a pain to do (for me anyway).

[mind_prepared]

I voted for the M2. Those PCBs always need their capacitors replaced, and that is a pain to do (for me anyway).

heh, I'm hearin ya, but isn't dismantling an M2 withouth breaking anything more of a pain the neck than replacing the cap on the original controller board? I mean, if you've gotten that far then a little soldering is probably not so much more pain to take after all, or is it?

I've been collecting a few M2s but I'm rarely seeing one on auction or elsewhere, not too many votes on here for an M2 replacement controller either. Nobody seems to really like the M2, what a pity.

[digital_matthew]

I voted for the M2. Those PCBs always need their capacitors replaced, and that is a pain to do (for me anyway).

heh, I'm hearin ya, but isn't dismantling an M2 withouth breaking anything more of a pain the neck than replacing the cap on the original controller board? I mean, if you've gotten that far then a little soldering is probably not so much more pain to take after all, or is it?

I've been collecting a few M2s but I'm rarely seeing one on auction or elsewhere, not too many votes on here for an M2 replacement controller either. Nobody seems to really like the M2, what a pity.

I've torn off the pads for the surface mount caps even though I was using heat and being really careful. Also despite using high-quality flux and a scalding hot soldering iron it's really difficult to get the solder to stick. But yeah opening the case is really hard too because you have to be careful about the clamps as well as the flimsy stabilizers on the keys. Reassembly is a bear as well. Overall they're vicious little keyboards to work on. I think the M2 would be more popular if their electronics weren't so shoddy; the form factor is great and I like the short key travel and crisp typing feel.

[cdaman]

I want to join in for M122!!