I had a 48S then a 49g+. I played around with a few games and a Magic Eye style (https://en.wikipedia.org/wiki/Random_dot_stereogram) 3D image generator, as well as programs to do actual math in my math classes. The math teachers teachers at my high school had a policy that, on exams, students could run any program they wrote, so I wrote programs to do the math and "show my work". Solving equations on paper was half of the grade, and getting the correct answer was the other half, but my handwriting is really bad, so I'd always get the wrong answer if I did it by hand.

HP's calculators are pretty capable, with built-in commands for image processing, so RPL programs could rival the capabilities of assembly language programs on TI-8x calculators.

Thanks for the reply.

I had asked because I was thinking of getting some small device like a PDA or programmable calculator, to use to write small programs for fun and possibly actual use, when I'm not with my laptop.

I am not sure if any PDAs or such calculators are still made these days. I have googled some, but so far did not find any, IIRC. So I may have to buy a used calculator or PDA, if I can find a model I like.

I used to have 2 different Palm PDA models earlier, first a V and then a Zire, but I never did any programming with them, although I do remember trying to use Pippy, a Python 2.x version ported to the Palm. But it used to crash all the time, so I could not really do any programming on it, unfortunately.