IEEE’s The Institute for December had a note in the calendar that on February 1rst, 1972 HP released the HP-35 pocket calculator. It was the first to compute trigonometric functions and logarithms.
I started college with an ancient Casio graphing calculator that died my 3rd semester. I didn’t have cash and so found a slide rule, went to the library and found books that explained how to use it, and used it for a few semesters. It was a hit with my mathematics instructors.
I ended up buying an HP-48G. The RPN through me for a loop initially, but once I caught on I wondered how I had lived without RPN for so long (still do!). I still have the 48G, but bought one of the new 50Gs for work. Unfortunately HP decided to change the layout of the keypad. I feel like the layout of the 48G was perfect and have a hard time with the 50G. Someday when I have time I am going to write a java2d calculator app that has the same layout as the 48G.