It's not really an answer to the Ask Slashdot question, but I don't see why one would want to use a non-approved programmed calculator.
The point of a calculator during exams is that you have a single tool with well defined capabilities, so as not to get an unfair advantage above students using a different brand of tool. For actual (professional) engineering calculations you will use a computer with decent programming tools (matlab, python, C/C++, or whatever your favorite is). In my 22 years of university (physics), scientific research, and industrial engineering, I have never felt the need for a fancy calculator. Nowadays I have RealCalc (Android app, clone of the decades-old Casio FX-8x line of non-programmable calculators) if I need a quick calculation during a meeting and a computer (combined with pen and paper) for everything else.
If your exams require that you have a graphing calculator, you'll probably need one. But I've never seen them used around me (R&D department counting a few thousand mechanical engineers).