It's not as unlikely as you would think. Electronic counterfeiters are often just ghost shifts at contract manufacturers. If a single company is handling the injection molding, PCB, and assembly, they can run a secret shift that makes units for them to sell themselves. Even if they can't get ahold of all the surplus parts they need, they can design their own.
Since the firmware is different, HP could have also outsourced production maintenance too (i.e. updating firmware if a chip reaches end of life and needs to be replaced with something that's not exactly compatible) which isn't unheard of for legacy products that no one wants to deal with.
Wikipedia has a lot of info. I'd like to know the serial numbers of the defective units.
One possible hypothesis is that HP switched to a new SoC, due to price or availability, and porting the firmware introduced some bugs.
Far-fetched but interesting possibility.
I wouldn't call this the simplest explanation. While they a vastly overpriced produce in 2024, its a niche product and I doubt sales are high. The simplest explanation an engineer was told to update the firmware and it had a side effect on the TVM function.
I have 2 HP-12c calculators which I bought while I worked at Goldman. One was always on my desk at work and I had another at home. I can certainly confirm they were common in finance back in 2000-2009ish. That said even back then they were being replaced by non-RPN calculators for a lot of people and only people with nostalgia and the hardcore had a 12c.
They're incredibly robust - famously a zookeeper once used an HP12-c to calculate proportions for animal feed, dropped it into the mix and it passed through the digestive tract of a hippo. It was still able to calculate the yield to maturity of a bond after cleaning.
In addition their batteries last forever. Even though the versions I have use the "weak" newer battery tech[1] they are both still on their original batteries and as I say mine are about 20 years old and at one point I used one of them every day. Having a slow cpu means they just run forever.
I now additionally own two other RPN calculators which I bought because I needed a scientific calculator and have a nostalgia for HP calculators because I used to write little programs for my dad on his. The 12c and the like don't have trig functions in particular so I own an HP35s and a swissmicros DM42[2], which is essentially an HP42S emulator with a faster processor and some enhanced capabilities based on Thomas Okken's "Free42"[3]. I would strongly recommend the DM42 for anyone who likes HP-style RPN calculators and wants a more powerful version. It's a fabulous calculator. Pretty much the only way the HPs are better is the feel of the keys which is too stiff on the DM42.
The HP35s is a great calculator also. Not as powerful as the DM42 but with that lovely classic HP key feel and a bit more usability for some things at the expense of being much worse to program, much slower and only having a 2-line screen. It does have a nice built-in set of physical constants though (which I never use).
[1] The original battery tech uses some sort of legendary toxic battery that is no longer permitted due to hazardous chemical regulations.
Alkaline button batteries used to contain mercury, which has been phased out in the last 20-25 years. The original Voyager line used 3 x LR44 (alkaline), but even then you could have replaced them with their less toxic silver-oxide equivalents. Today's LR44 cells are mercury-free.
Later iterations of HP12C use 2 x CR2032, not because of any concerns about toxicity -- the 2032s were equally toxic -- but, I suspect, because the original battery controller was all custom HP silicon in some funky semi-analog process, which couldn't survive when HP, along with the rest of the industry, fully succumbed to cost-cutting disease. Everything possible in the new calculators if off-the-shelf.
To be fair, lack of self-discharge in the battery chemistry has a lot to do with the long battery life; you can actually drain the batteries fairly quickly with long-running calculations.
> describing some difficulty changing the decimal point to a decimal comma on a new Brazilian-bought HP-12c
Perhaps some wrong constant has been put in the firmware as a result of mixing up the command and period.
One thing comes to mind though: back when this calculator was acquired (my wife was doing her MBA) a professor warned about being tempted to buy the Platinum version, as it would yield wrong results and, if that happened in a test, it'd result in the student failing. I think that, back then, the Platinum was the first to run on ARM emulation.
Prima facia, the way Id tackle it if I have a few extra registers is
1. Id write the exponent as n = R*m, where R is an integer. R = 2 is probably best.
2. Then Id do pascal's triangle (every element is a simple combination comb[x,y]) for the expansion of the exponent (if R = 2 binomial expansion) and add in ascending order.
3. Then raise the answer to the power of m.
Of course, I can iteratively do steps 1-2 if the interest rate is very small.
But running this may be possible: https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.c...
