When I went to college in the fall of ‘73 they were teaching engineering students like me how to use slide rules. But the HP-35 scientific calculator had been introduced in 1972 and a few other students had them. It was an amazing thing. The HP web page (linked above) says:
HP asked a local market research firm to do a market study. They did and determined that the HP-35 Scientific Calculator would never sell because it was too expensive. Bill said “We’re going to go ahead anyway.” The product was so popular that HP couldn’t make them fast enough.
Bill remembered, “We figured, in the first year, if we could sell 10,000 calculators, we’d break even. We sold 100,000.”
I played with one for a little bit and then went to the University Book Store and bought one. It cost $300. That was a lot of money then. An entire year of school with books, tuition, room, and board was on the order of $2000.
I brought it back to my dorm room and the engineer across the hall from me came over and we played with it until dawn. It was absolutely amazing.
I eventually owned several different HP calculators. I programmed them and spent a lot of time “crunching numbers” for my electrical engineering problems.
I had gotten at least two different battery packs in the late seventies for my ‘35 when the old NiCads died and then ran it on the charger for years. The power switch got a little flakey and some of the keys got some bounce in them and I would have to sometimes fiddle with it to get it to work right. But it always would come through for me.
My HP-35 sat on the shelf a lot after I got newer calculators but when I set up my reloading bench back in the mid ‘90s I got it out and left it there. I would use it for estimating how many rounds I could get from a pound of powder or muzzle velocities and “power factors” from alternate powder charges or bullet weights.
As I was unpacking my gun room today I plugged it in and it would not turn on. I don’t know if it is the power supply, the power switch, or something else. It doesn’t really matter at this point. As of last month I have had it for 40 years.
I have another HP calculator I’ll put on my bench. If it lasts 40 years from when I bought it then it should last for at least another 10.