IBM 1391401: The Classic Model M

When someone says ‘Model M’ without further details, this is the keyboard they are talking about: the 1391401. This was my first buckling spring keyboard and it has served well since. It was definitely responsible for a lot of my interest in buckling spring keyboards.

The Model M was never referred to as such in marketing when it was new; this is a colloquialism based on how they are labeled, and a retronym of sorts for keyboards built with the same construction even when not labeled as one. The actual product name for the keyboard is the IBM Enhanced Keyboard, as it has an ‘enhanced’ layout compared to its predecessor in the PC realm, the AT.

In this sense, “Model M” is a deceptive name. “Model” tends to suggest a unique offering; that all keyboards marked “Model M” would be the same, and perhaps many of models A through L and N through Z might be built with the same technology but differing layouts or features. In reality, the part number is what designates these unique qualities, and “Model M” seems to refer more to the mechanism within

  • Identification: IBM part number 1391401, ID number 8821502, designated ‘Model M’, manufactured in USA by Lexmark 1993-08-30
  • Application: IBM PS/2-compatibles
  • Connectivity: PS/2 interface with detachable cable (6-position SDL connector at keyboard)
  • Key layout: 101-key US layout
  • Keyswitches: tactile and ‘clicky’ buckling spring over membrane
  • Acquired: 2004, freebie from secondary school

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