IBM used lettered model designations for its IBM Electric series of typewriters
and various IBM keyboard families. You may be familiar with their Model F and Model M keyboard families, but obviously, there were letters before those. IBM Electric Typewriters Models A through D, and IBM keyboards Models A through M. There are also some models that sat adjacent to the letters like Typewriter 01 through 10 and Keyboards 1A and 1B.
This nomenclature was reset between the “typewriter age” and the “electronic keyboard age”, resulting in some overlaps (for example, a Model B typewriter family and a Model B keyboard family exist). I’ve also seen some people consider that keyboards extended the typewriter nomenclature beginning at “Model F” (as something like “beamspring keyboard = Model B” is not as widely known as F or M.) This page addresses this, describing what all the models are (and offering theories for the ones we don’t 100% understand like IBM Model A keyboards).
https://sharktastica.co.uk/topics/modelsEnjoy!
