In the early 80s my brother had the coolest calculator, the HP 41cx. My middle school class was the last one to have learned how to calculate on a slide ruler. I still can compute basic stuff on it, or so I make myself believe.
But then, electronic calculators got cheap enough and everyone switched to them. The most popular at my school was the TI-30, at first with diode and a bit later with liquid crystal display.
Calculators from Hewlett-Packard and their owners where in a class of their own, because HP used Reverse Polish Notation (RPN). Although not really complicated (you just had to sit down once and figure it out), it seemed to be just beyond the grasp of most people. They would come up to the desk and say, “Can I use your calculator? – Oh, you have an HP” and move on to the next table. HP calculator owners where like a little club of the ones who have figured it out; and RPN their secret handshake.
Actually, I didn’t own one but my brother had the coolest of them all, the programmable HP 41cx. Not only could you write your own little programs, but you could save them to little magnetic strips. I spent hours and hours on it. It was just plain cool.