HP calculators have long been on my list of things that just really impress the heck out of me. I bought an HP-45 when I went off to the first (and only) year at USC. (The HP-45 was a more full featured version of the revolutionary HP-35.) I had worked all summer debugging weird operating system problems with minicomputers, and used part of my miserable $80 a week pay to save up for this gem. For those of us who grew up using slide rules (and carrying them in holsters on our belts) to solve physical science problems, this was such a leap forward--no more trying to figure out where the decimal point went in the mantissa! (Is this .003 Newtons of force? Or 3000 Newtons of force?)
This was back in the bad old days when manufacturers had enforceable "fair trade" agreements that prohibited most stores from selling HP calculators below the manufacturer's "suggested" retail price. In practice, the HP-45 was $395 everywhere you went, except at university bookstores and a few other places that required to prove that you were faculty or student. My HP-45 at the USC bookstore was $309, with sales tax--and worth every penny, since I was taking chemistry and physics that year.
That HP-45 served me well, until it was burgled, along with my German hyperinflation 100 million mark note. (I'm sure that the burglar was quite disappointed to discover that he couldn't exchange it at the then current rate of four marks per dollar.)
I bought an HP-27 calculator, which was a mixture of scientific and business functions with the insurance company's payout--and had money left over. I loved that HP-27--even smaller and more powerful than the HP-45, but eventually, the NiCad batteries wouldn't recharge, and then the charger wouldn't recharge new batteries. I gave the calculator to a buddy, who sold it at a swap meet. The box and manual I sold on eBay a few years ago for more than $200 to a Hong Kong collector of such stuff. I wonder what the calculator and recharger would have fetched!
Perhaps seven or eight years ago, I bought an HP12C, primarily to do financial calculations (loan payments, that sort of thing). I bought it because I have always been a big fan of RPN calculators--the equals sign is the mark of an inferior and less powerful calculator, as far as I am concerned.
RPN stands for Reverse Polish Notation, so called because no one (except a Pole) can pronounce the name of Jan Łukasiewicz, the Polish mathematician who developed the prefix operator method of defining mathematical equations without parentheses. (RPN is a postfix operator form that also gets rid of parentheses.) Computer geeks just seem to take naturally to RPN, perhaps because we learn very young about parsing techniques that involve converting complex combinations of parentheses, values, and operators into RPN-like stacks.
Anyway, this HP12C has served me well, but the original batteries finally gave up the ghost yesterday. I am absolutely sure that I have never replaced them; when I opened up the battery cover, I was surprised to find three LR44 watch batteries snuggled up like they were sleeping on their sides.
It turns out that HP has brought back as a weird kind of nostalgia item the HP-35s--and I must confess that I wouldn't mind having one. (For the scientific functions that the HP12C doesn't have, such as trig.)