EEVBlog #1159 Dave Jones reviews the DM42

[Didier Lachieze]

(12-19-2018 06:49 AM)Tugdual Wrote:  Interesting comment from Dave on the keyboard construction. I somehow believe that the original HPs had a hinge on each key while on the dm42 it is a plastic bloc that is bent.

The change from individual keys to a key frame happened with the Pioneer series, so the original HP 42S (and later on all HP 48 models) has a similar keyboard construction to the DM42.

Here is a detailed picture of the 48SX construction from the June 1991 HP Journal:

The topcase of the HP 48SX is a four-color, injection molded part. Its 49 keys are an integral part of the topcase; each key is attached and guided by two small cantilevers.