Why does the 35 have blank keys?


I am wondering the reason why the early hp35 have blank keys.
The only reasonable though I had was that until the last moment they didn't know which functions would be implemented and thus could not design the keys.
I am sure however someone will have a better answer.




Remember how early this was. :-)

My SR-16-II in 1976 had blank keys.

Injection moulded keys eventually became the standard, but 1972 was very early.



Your guess might be pretty close.

Shortly after the '35 appeared, I was part of a group of grad students at Caltech that had lunch with Bernard Oliver (VP of HP at that time), and of course the hot topic of conversation was the new calculator, which we all lusted after but couldn't afford (it cost about two months of a grad student's stipend at that time!).

One of the questions concered how the functions were chosen. Oliver said that there had been a bread-board calculator attached to a computer, and that HP engineers (of all types, I guess) were invited to create a "button" for whatever function(s) they wanted/needed, the functionality of which would then be implemented in the attached computer.

After enough folks had picked functions, their choices were basically treated as votes for the most-useful functions.

So, it may have been that they didn't know what functions would actually be included until almost production time.


A keyboard silkscreen costs a few bucks to make and can do a lot of calculators. A set of injection molds costs over $100,000.


Why are the molds so expensive? I thought that you could download a file from a CAD program and get just about anything machined at a reasonable cost.


quote "Why are the molds so expensive? I thought that you could download a file from a CAD program and get just about anything machined at a reasonable cost."

Well, we are talking about 1971 (this is when the calculator was designed) - I assume they did the molds mostly by hand then. And double-shot molds are not exactly easy stuff. Plus you have to remember: the 35 was not intended to be a mass-produced item, using blank keys was much cheaper.

Btw. I have a prototype 45 with engraved keys - so they finalized the design before creating the molds (which probably means, the molds were still expensive then...)


This Message was deleted. This empty message preserves the threading when a post with followup(s) is deleted.


Take a look at the article by Edward T. Liljenwall, industrial designer of the HP-35, in HP Journal Jun 1972, pages 12-13. (There you can also find two articles by HP-35 hardware and software designers):


Edited: 4 June 2005, 9:01 a.m. after one or more responses were posted


Very interesting indeed.


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