HP-12c Platinum
HP-12c Platinum
HP's most accurate financial calculator, oddly enough, and despite only returning the ceiling of solve-for-n.
My dad was a surveyor almost my entire life, he always had this (or a very similar model) in his pocket or on his desk.
As a surveyor, he probably had an 11c or 15c (the 12c is the financial version of the Voyager series).
Aside: Swissmicro sells a series of voyager clones with modern hardware:
https://www.swissmicros.com/product/dm15l
More info on the original HP calcs:
https://en.wikipedia.org/wiki/Hewlett-Packard_Voyager_series
I looked at an image of the 11c, that was it for sure.
That's lovely - these calculators are very 'dad' style to me also (though my dad had a 70s style Casio). There's something about the voyager HP calculators with their landscape format - they are really satisfying to use, I can see why he kept it on him!
It is absolutely gorgeous, but I've always been confused by financial calculators. The buttons are all gibberish, and I have no idea what they do. I've got a TI-BA II Plus in my collection, but I think I've only turned it on four or five times 'cause I get scared.
I always thought of financial calculators as a sort of gelded single-function function machine and I didn't really get them. However, that would ignore the vast number of models available from HP, and that their second ever pocket calculator was a financial one. It turns out that solving the time value of money equation is non-trivial, and the work done on that probably paved the way for calculators with a solver.
The other thing I didn't appreciate until I had to use it, is that the interface of the 12c - with the 5 buttons in the top left for n, i, pv, pmt and fv is peak user interface. Press once to input data, but a second consecutive press of these buttons will trigger the solve and drop the result into x. It's perfect, and means you can solve and use all the calculator functions and stack continuously. Most modern methods use a table, which is hard to extract and input information from the calculator.
Obligatory "what pen is that?"
It's a Stilform fountain pen. They are a recent make using machined parts and bock nibs with a nifty magnetic cap. I'm having slight issues with the bock nibs though - they are going to need a bit more work to keep the flow how I like it.