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 inven

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.