I was searching for calculator resources just now and came across The HP Memory Project. I'm certain that site must be familiar to many of you, but it was new to me. I noticed that they have "new" sections devoted to desktop and pocket calculators. I've only read the beginning section on the HP 35, but the pocket calculator page promises to be a detailed and interesting walk through the history of HP's pocket calculators from the HP-35 to the HP-41C.

Something that really caught my eye is an excerpt from INSIDE HP: A narrative history
of Hewlett-Packard from 1939-1990 (PDF link) written by John Minck. Mr Minck was a technical marketing exec at the HPA division. He describes the calculator project that an HP customer called Unidynamics had underway, but then abandoned. Mr Minck is the guy that subsequently passed the information on to HP labs. This then led HP labs to create a design using HP ICs that became the HP-35.

Apologies if this is already known to most of you. It might be worth a re-read, even so. :)

Regards,

Howard