Back in the 90's, I created something like a mortgage calculator on my HP48gx. It was about 1500 "lines" (a line being maybe at most 30 chars) , all keyed in using only the calculator. The mind is capable of many things.
The HP48 has a pretty good keyboard. I remember someone who typed as fast as most people would do on a full keyboard, using some weird kind of touch typing with the hands vertically positioned on both sides of the calculator.
The problem is more about the software. The HP48 is pretty slow, and has a tendency to lose your data a bit too easily. There are some editors written in assembly that are good enough though, and since you had a GX, you could use memory card backups.
Yes, the keyboard space was large enough that you could get into a routine of using both hands. Scrolling through the code was a nightmare though, it was not the fastest IDE at the time.
I wrote a few programs on my HP48GX (which still works perfectly). Programs about Maxwell formulas and Einstein's effects where a little bit more complicated. Not once did I think, "But this is exhausting!". However, I stayed under 1000 lines.
But now, if something gets a little bit more complicated or repetitive in my cozy Neovim environment I think more about how to avoid this with ChatGPT, Cursor, Windsurf… maybe a restrictive environment is sometimes better to actually build something?
My HP48 from high school (90‘s) is one of my prized possessions. It still works.
And I still can’t use a calculator that does not use Reverse Polish Notation…
I was looking for a reference but I am afraid it is lost in some news group in the distant past but my understanding is that all of Meta Kernel was written directly on an HP calculator.
