deskthority

This is supposed to be the M version of the IBM 4704 Model 100 keypad. It sports the gray IBM oval logo, has a plastic backside and M's flip-out feet, and even sports an SDL plug.
Yet... typing on it feels quite closer to typing on a Model F than on a Model M.

Why?
A quick topside look at the springs doesn't yield much, so... let's open it.
Frontside doesn't tell us much.
Is this a SHINY backplate? Like Model F units had?
The controller looks like an M-era model...
... the sandwiched foam, on the other hand, screams of Fness.

And with that, I stop. If I open this up, I'll surely won't be able to put it back together.

I bought this keypad as a fun toy, to use as a side pad or a sophisticated game pad of sorts; I did not expect it to bring this pleasant surprise. What a fun... hybrid? intermediate evolutionary step? keypad.

I now kinda want to procure one of the later models, manufactured by Lexmark, if only to see if typing on it would feel more like a Model M than a Model F.

If somebody makes a PCB for this, then it would be able to make a semi-model F.
Or if you want a bigger project, then you can try to build build an ergodox model F using two keyboards.
By the way, feet are different from those of regular model M as I remember.

Hard to tell with the flash, black flippers would point towards an F, white are a pretty surefire sign of an M.
139* part numbers are associated with model M.
The controller photos clearly show two superposed membranes; it should be possible to lift the foam slightly and see the PCB on an F as well.
Individual barrels on an M are peculiar, are there other known examples?
We did see that plastic barrel plate style F typewriter assembly not long ago, so there is some overlap in the techniques on both models.

It's definitely a Model M, I've got one and opened it up before and it's membrane is exactly like an M. If anyone could design a PCB I'll love to test turning this into a full F.

Darkshado wrote: We did see that plastic barrel plate style F typewriter assembly not long ago, so there is some overlap in the techniques on both models.

That's the interesting part, thanks for posting depletedvespene!

IBM, would it really have cost that much more to keep the M like this!

You had the tooling to automatically assemble F's i have seen the vids .

Does switching to heat melted plastic really same that much money ?

And don't forget , you can make almost all the spare parts for your existing customer who have F's on the same production line!

Great find! Those keypads have a really distinctive feel. Maybe is not the same, but mine (that we talked about months ago)
has a strong bottom feeling like short travel switches (for example the short travel futabas), accompanied by a TAP sound. Anyway, would be interesting see it working. Do you checket his compatibility?

The one in the pictures is already in active usage by my son. I haven't started using the other one (as I want to clean it a bit first), but I expect it to work just as nicely. At least the typing feel is the same.

IIRC, your unit must be Lexmark made - mine are a bit older, IBM made, and it may be that your unit does have a typing feel like the regular Model M keyboards. We need to determine it for sure.

Mine is blue label, so your board is older. I put it in front of my daily use battle cruiser and they definitely sound and feel different. What I mean is that these "planck" IBM's are a whole different world.

This looks to be similar to the "hybrid Model M/F" in the screenreader keypad here: photos-f62/ibm-model-m-os-2-screen-read ... 13488.html

Sorry for reviving this, but I just noticed today that mine is a M/F too. You can easily notice that by the swinging of the barrels. I did not expect that of a blue label, but it's awesome anyway.

I also found one and can confirm the switches really snap nicely, much more like an f than an m.. So theory is that's because the metal plate joints? Tent:wq

Is there any f50's PCB existing? Maybe could make some mod for an M50.

tentator wrote: I also found one and can confirm the switches really snap nicely, much more like an f than an m.. So theory is that's because the metal plate joints?

Yup, that's what I think.