Actual physical objects made of stuff · Computers · Flat Things

Can you swap the keyboards between a Thinkpad T40 and an IBM SK-8845?


(I’m posting this because it’s something I searched for and didn’t find an answer to.)

The SK-8845 and its sibling the SK-8840 are IBM-branded keyboards with built-in trackpoint and trackpad.

They appear to be essentially the keyboards from Thinkpad T40 (or T41, T42, T43) laptops, pulled out and put in a separate case for use as a compact keyboard/mouse controller in a server room. They’re pretty good keyboards in a classic Thinkpad laptop sort of way.

I have an SK-8840, which is the (less common?) PS/2 variant. As far as I can tell from photos, without having seen one in person, the SK-8845 is the same keyboard with a USB plug on it.

Here’s the SK-8840:

IBM SK-8840 keyboard. I’m sorry, I removed the trackpoint. I always do – I never use it and it gets in the way a little. I do keep the trackpoints in case I want to sell up though. Have you noticed the trackpoint pin is rotated 45° from the normal Thinkpad keyboards? I wonder why.

Visually this is much the same as the keyboard on the T4x series of Thinkpad laptops, which are truly excellent. It doesn’t feel like a T40 keyboard though. It’s more like the later, still good but not quite so good T60 series. So I wondered whether it was possible to swap the keyboard part with that from (ahem) one of my T4x laptops.

The answer is no: it’s physically incompatible. The plate at the back is different, the connections are different, the stand-offs are different. It may be possible to adapt one into the other and that could be an interesting project for someone more ambitious than me, but it definitely isn’t a case of just pulling out the keyboard part and plugging it in. The same goes for the T60.

Here’s the innards, and the back of the keyboard plate, of the SK-8840:

Here are the backs of the keyboards from a T40 (above) and T60 (below):

That’s all.

2 thoughts on “Can you swap the keyboards between a Thinkpad T40 and an IBM SK-8845?

  1. How about using the t42 key parts on an sk-8840 or sk-8845?
    My sk-8845 has quite a few keys missing and some those missing keys are also missing the underlying plastic scissors.
    The dome nubs are clear plastic, the scissors are a black plastic. The nubs still work when pressed.

    1. Good question. (Though for some reason the idea of removing just a few keys from a T40 seems more cruel than removing the whole keyboard!)

      Hard to say for sure, since T40 and T60 keyboards were made by various manufacturers with different switches and keycaps and I have never taken the trouble to learn how to tell them apart. But at least with the models I have available, the answer is no – I removed a keycap from my SK-8840 (whose innards look much as you describe), a T40, and two different T60 keyboards and found none of them to be interchangeable. A proper answer would take more resources but the chances seem slim.

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