A new Shark’s Wiki page - IBM Model M3! The keyboard and keypad for the early IBM notebook PS/2 Model L40SX.
I say “new”… this wiki page was originally just the keypad and was written a while ago, not up to my present standards. Anywho, the IBM Personal System/2 L40 SX was perhaps the most well known of IBM’s pre-ThinkPad notebook laptops. It didn’t obtain much commercial success, but its keyboard was widely praised in the press at the time and in contemporary reviews by Nostalgia Nerd and Wendell at Level1Techs.
Its keyboard and keypad - IBM Model M3 - was the first vessel of IBM’s “buckling sleeve” keyswitches, a major research interest of mine. The keyboard and keypad design were subsequently adapted to become IBM Model M4/M4-1 (IBM Space Saver Keyboard & Numeric Keypad) and evolved into IBM Model M6/M6-1 (the first IBM ThinkPad Keyboards). The L40 SX and its M3 represented a major shift in the Model M keyboard family, creating a lineage within it more suitable for portable computers but not yielding to traditional rubber dome designs as well. Obviously, how good they are is subjective (like anything), but I think it is hard to argue against how the ThinkPad’s early reputation for keyboards that endures today was built by laptops with M6/M6-1 keyboards - and there is no M6/M6-1 without M3!
(From PC Mag, August 1991)
Enjoy!