I find these calculators fascinating. I'm not a computer scientist, but I find it really intriguing that their processors naturally handled binary encoded decimal, and also their algorithms for calculating trig and log functions on such limited processing power. I understand the early HPs excelled themselves on returning accurate results, often more accurate than more modern machines.
Day to day I use free42/plus42 on my phone for working out quick calculations. I find the RPN works best when you're trying to solve numerical questions as you go. It also has great time/date functions which help me to plan driving trips etc, and it is programmable, so I have a few useful calculators on it for EV charging etc.
The 50g remains the best calculator I've ever used. I've also got a prime, and while it may be faster and come with a larger library, it feels so much more limited and clunky.
Many emulators for these old calculators go out of their way to be as skeuomorphic as possible, using JPEGs of the actual calculator hardware. While some people may enjoy that, I appreciate that these emulators don't make the effort. My dream has always been a 50g emulator in this style.
The skeuomorphism comes in handy sometimes: the 50g emulator on my current smartphone reproduces the keyboard at ~94% scale, which is close enough that muscle memory transfers over. But for use on a desktop computer, I agree that the skeuomorphism is not necessary.
> It not only runs (included) ROM code from the HP-45, but also the HP-35 and the HP-80
I thought that ROM code is copyrighted and cannot be redistributed without permission. Maybe they got that permission from HP. The TI calculator emulators require a separate ROM dump from an actual physical calculator.
Day to day I use free42/plus42 on my phone for working out quick calculations. I find the RPN works best when you're trying to solve numerical questions as you go. It also has great time/date functions which help me to plan driving trips etc, and it is programmable, so I have a few useful calculators on it for EV charging etc.