Choose an engineering (programmable) calculator?

Question

Iron

To study, you need to buy a good calculator, in my head I immediately remembered an article on Habré, where Doom was launched on a calculator.
So, advise a calculator, I didn’t find anything sensible by googling ...
It would also be nice if he could read at least .txt files. So you can write off :)
The budget is $ 50-100, I will most likely buy from ebay.

Answer 1

TI 83, TI 84, TI 89 are the hardest, they cost about that much money on the go.
If for life - an ancient PDA on wm 5 makes the calculator work no worse, plus there is a lot more.

Answer 2

And what will you do with it? There is no sense in writing at the exam of the megaprogram, for a long time, just in life and PDA-like devices can be used, but rather the same matlab and the like. I just see a lot of people around with such calculators and it doesn’t go beyond calculating the simplest things, so why pay more? :)