The HP-35 Design: A Case Study in Innovation (2011) [pdf] (opens in new tab)

My dad had this calculator in the 70s. He was an engineer for the local power utility and told me that before getting the HP-35 he would submit calculations at the computer center and get his results back about a week later. With the calculator he could run his computations immediately, at his desk. It was life changing, at least in the context of his work.

It was one of the more expensive small things he owned so he never left it at his desk, carrying it around in his jacket pocket (engineers wore suits to work in the 70s). He told me he also got a reputation for this, since it was such a unique thing to be carrying around.

Very well written and makes me realize what a pioneer company HP was at that time. It was the Apple of its time. Best anecdote:

> Stanford Engineering Dean Fred Terman, the person responsible for bringing Bill Hewlett and Dave Packard together to start HP was one of the first. He was overwhelmed, looking for an umbilical cord connected to a big computer doing the precision calculations.

I bought a used one in the 80's and found it an amazing device: simple yet powerful. A Turing Complete pocket computer. It should be noted that HP did NOT invent reverse polish notation, and the HP-35 allegedly borrowed a lot of ideas from the Olivetti Programma 101 computer, arguably the first desktop computer.

Still, the HP-35 was an amazing packaging of existing but relatively new ideas (at least as actual products). This kind of thing is what made Apple big: take different new but existing ideas and combine and package them well by keeping the good and tossing the bad or low-use features. Steve Jobs had a nose for how to use new ideas invented by others by carefully picking, choosing, and associating features. What you leave out is often more important than what you put in.

I've also read that HP was hesitant to advertise such devices as "computers" because that carried export restrictions per military concerns. Calling it a "calculator" got around that. The convention of defining "computer" as something Turing Complete came later I believe.

Very interesting article. My dad, an engineer, had the successor to this model, the HP-45. It was an amazing machine for it's time. Because of it, I fell in love with RPN and refused to use anything else. When I went to college I got an HP-48sx. I think it was the zenith of scientific calculators with so much functionality crammed into it.

Really enjoyed that.