My article on the IBM Model M4/M4-1, desktop predecessors to the OG ThinkPad keyboard [WARNING: photos]

[sharktastica]

Hi!

Hopefully, this is an acceptable place to post this. I thought a few might be interested in reading about these keyboards, being some have TrackPoints and they developed from and into various IBM portable PCs. This is the story and (aiming to be) definitive article on the IBM Model M4 and M4-1 Space Saver buckling sleeves keyboards, the keyboard that came before and largely inspired the first generation of ThinkPad keyboards (the Model M6). Well... sort of. The story is a bit more complex but everything is explained inside! This has been one of the largest undertakings for my website, being over a month in the making, and features contributions from several awesome people! All contributions are acknowledged at the end.

The motivation for this was that there is seldom (centralised) information about these keyboards. They're not particularly rare nor unheard about, but in my time looking up these keyboards, I noticed a fair few misconceptions and a lot of questions gone unanswered. Being someone who particularly loves these sorts of nichés and nuances, I thought this would be a cool thing to write about.

The article: https://sharktastica.co.uk/articles/m4_story. FYI, there's a lot of photos inside.

Enjoy! Feel free to let me know what you think.

[axur-delmeria]

Another well-written article.One question: do you know the last Thinkpad model that had the buckling sleeve keyboard?

All your articles about IBM keyboard technologies make me wish there was a way to replicate these designs and allow one to fabricate custom buckling spring/sleeve keyboards.

[sharktastica]

Another well-written article.One question: do you know the last Thinkpad model that had the buckling sleeve keyboard?

All your articles about IBM keyboard technologies make me wish there was a way to replicate these designs and allow one to fabricate custom buckling spring/sleeve keyboards.

Thanks!

I'm not 100% sure what the last buckling sleeves carrying ThinkPads was, but it's likely a model from 1998 since that's the last year I've seen a Key Tronic "M3/M4/M6-type" buckling sleeves keyboard produced in. Whilst Unicomp produced M4s for many years after, I've never seen an M6 from them nor has Unicomp ever communicated the fact they made any to me. If they had, I'm pretty sure they would have mentioned it as a part of their heritage. Whilst I'm sure I've seen one before, I had an impossible time finding a photo of a Maxi Switch M6. From my memory, it was from 1995 though so not much help. The other factor is Key Tronic's own buckling sleeves implementation. I've only seen that on the 701C/701CS though, and since that's from 1995, it doesn't help with this question. I assume Key Tronic didn't continue using this implementation since they acquired the "proper" one from Lexmark in early 1996. By most accounts I've heard, the 701C/701CS sleeves were not as good as the M3/M4/M6 type as well.

Trying to work this out by looking for the first non-sleeves also doesn't help. My 760CD has a late 1995 keyboard assembly that uses these "rubber peg" switches, which complicates this timeline. If there's one thing I've learned from authoring my website and trying to figure stuff like this out is that IBM's keyboard development timeline is a complete mess and jungle of nuances; from their first discrete Selectric printer-keyboards of the '60s to Model Bs to Model Fs to Model Ms to ThinkPad keyboards... But, I guess this is what makes research fun!

[axur-delmeria]

Thanks for the info!

I better check the 560E keyboard I have. Too bad I don't have my 760XD anymore.

[sharktastica]

Thanks for the info!

I better check the 560E keyboard I have. Too bad I don't have my 760XD anymore.

Cool! Lemme know what sort of keyboard it has!

[sharktastica]

Update: Along with some minor spelling and grammar improvements, I've added photos of a Lexmark-branded M4. Thanks to deskthority user arkanoid for offering these photos for the article!

You can go straight to it here: https://sharktastica.co.uk/articles/m4_story#OEMs