Most of what I know comes from listening to other engineers (my father's age) talk as I went through engineering school with a TI Voyage 200. That didn't have a

Most of what I know comes from listening to other engineers (my father's age) talk as I went through engineering school with a TI Voyage 200. That didn't have a nice manual, but it had pretty printing and could solve large systems of complex equations with ease and was almost too powerful and even came with apps (essentially a TI-89 with more RAM and a lot more buttons). I could type out a massive equation and then adjust it slightly each time. My father was dirt poor and worked in fast food full time while taking classes, and he could somehow afford one as did most of his classmates as the RPN feature would be invaluable when a TI calculator would force you to write down output from individual calculations without an X-Y-T stack (please correct me if I'm wrong though). Another advantage to owning one was some introductory programming classes would allow you to use the HP language for homework assignments. As ridiculous as this sounds, the alternative was waiting in a massive line at the computer lab to use the Unix time-sharing system (apparently the university had one of these) to run your Fortran or Pascal code.