Vintage HP45 calculator

[MRMILSTAR]

I bought this HP45 calculator in 1974 while attending college. This was only the second pocket scientific calculator made. The HP35 was the first. I still have my HP45. It is in perfect condition as can be seen from the picture. I had to replace the original NiCD battery pack with NiMH batteries because of age but other than that it works perfectly even though it is 49 years old.

This calculator was like science fiction when I got it. I had previously used a large Pickett slide rule. I never used the slide rule again. I paid $395 for the HP45 in 1974 which in today's dollars is about $2400 so it was a real luxury item but I had to have one and I never regretted the purchase. It uses the RPN system of calculation which I greatly prefer over the competing algebraic-entry calculators that relied on paranthesis entry.

I also have a mint-condition HP41C which I bought in the early 1980s that I still use because its battery life is longer than the HP45. Its a real shame that HP stopped making these fine calculators which were unmatched. Even today nice vintage ones like mine sell for $150 and up on E-Bay.

[klugesmith]

Yay for RPN in calculators!  It absolutely saves keystrokes.

In high school, a couple of my wealthier friends had HP35 and HP45 calculators.  Remember the easy-to-demonstrate arithmetic error case?
My first HP calculator was, I think, a HP29C purchased around 1976.  That was a transition period where they had CMOS memory (for continuous storage of saved programs) but didn't yet have LCD display technology.

[davekni]

My mom was given an HP45 by her aunt back then too.  My brother has it now.
A friend gave me an HP35 who's battery pack had leaked badly.  It still works with wires to an external wall wart supply.  On/off slide switch is a bit finicky.

HP's internal calculation engine was fascinating too.  Single bit ALU.  Working register set is all serial shift registers.

[MRMILSTAR]

Yay for RPN in calculators!  It absolutely saves keystrokes.

In high school, a couple of my wealthier friends had HP35 and HP45 calculators.  Remember the easy-to-demonstrate arithmetic error case?
My first HP calculator was, I think, a HP29C purchased around 1976.  That was a transition period where they had CMOS memory (for continuous storage of saved programs) but didn't yet have LCD display technology.

I recall someone showing me an arithmetic error on their HP35 but I am not aware of one on the HP45.

RPN is slightly intimidating to first-time users because its not obvious how it works. They always ask "Where are the "=, (, and )" keys???"  After about 10 minutes of use though they totally understand why its so much better than the algebraic-entry calculators.

I now use my HP41C because it has an LCD display which greatly extends the battery life over that of the HP45 with its LED display. I also have a vintage TI59 with full accessories that my employer in the late 1970s (Texas Instruments) gave me. It has a built-in magnetic card reader.

[klugesmith]

Here's an HP-41 calculator with special application overlay, used in the U S Navy's P-3C patrol airplanes.
Seen in museum at Moffett Field in Sunnyvale, CA, once home to the dirigible Macon,
and home to the Pacific patrol fleet until 1993. I just noticed that the carrying case from HP is still with it.