I fiddled with an HP Reverse Polish Notation calculator for about 30 minutes....THEN I got the hammer!
Seems to me the main idea of a calculator is for the Calculator to make it Easy for me NOT the other way around
HP calculators were also quite tough: a friend had his HP-35 stolen, and when the thief was found he was trying to flush it down a toilet. The calculator worked fine after a new battery and wipedown with clorox.
RPN vs algebraic was very much a religious dispute, ended when Carly Fiorino ruined HP
Pictures of which? I am quite disorganized with this stuff, so I don't have everything in the same place.
There is even a Texas Instruments Real Estate calculator I have some place.