https://dm319.github.io/pages/2024_09_09_hp12_comma.html
The HP-12c is probably the most iconic financial calculator. Not being in finance myself, and in fact being terribly bad at that kind of thing, I never quite got the purpose of these special-purpose devices. My ignorance came to a halt due to an unfortunate combination of my fixed-rate mortgage period ending and Liz Truss happening, and I was driven to a sudden keen interest in the 'time value of money' (TVM) calculation.
...
Earlier this year I came across a fairly benign-looking reddit post describing some difficulty changing the decimal point to a decimal comma on a new Brazilian-bought HP-12c. Most of the replies were along the lines of 'you're holding it wrong', but something caught my attention. They weren't the only one, and not only had someone else had the same experience, I was pointed to numerous Amazon reviews describing similar woes.
To find out for myself, I VPN'd myself over to the Brazilian Amazon and started reading (with the assistance of my phone and google translate) reviews. What I saw was quite consistent - people couldn't change the point to the comma, and the calculator also failed on something called the internal rate of return (IRR) calculation.
I was curious, were these a different version of the HP-12c? Was it a fake? It is generally accepted that the HP-12c (and to some degree the related HP-12c platinum) will return exactly the same results no matter. Why would it otherwise? It was at this point I needed help, and a very kind Brazilian redditor did the work needed to run the aforementioned TVM tests as a forensic tool. What they found was a set of results entirely different to not just the regular HP-12c, but to any other financial calculator we had tested.
(Score: 2, Interesting) by Anonymous Coward on Wednesday September 18 2024, @10:21PM
Were they able to change it to a comma?
(Score: 2) by DadaDoofy on Wednesday September 18 2024, @10:59PM (2 children)
Perhaps some background is in order. Hewlett and Packard were a couple of Stanford trained electrical engineers. In 1939, they formed a scientific instrument company in California called Hewlett-Packard. In the 1970s, they produced what many consider to be the finest electronic calculators available during that era.
At that time, what we know of today as "localization" (https://learn.microsoft.com/en-us/dotnet/core/extensions/localization) was, for the most part unsupported. It would be several decades before electronics and software were designed to support what today is the expectation.
(Score: 0) by Anonymous Coward on Wednesday September 18 2024, @11:20PM (1 child)
"new Brazilian-bought HP-12c" is the key
the 12C has been re-implemented many times so it would be really unlikely they deliberately left out
internationalization of currency.
(Score: 3, Insightful) by HiThere on Thursday September 19 2024, @12:26AM
Re-implemented is likely to have brand new bugs that weren't in the original.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 5, Interesting) by datapharmer on Thursday September 19 2024, @02:24AM (1 child)
This calculator is legendary but has some flaws known by those who use it regularly. The most well known is the rounding of fractional annuity data to the next integer which makes the calculation useless. See: https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv005.cgi?read=8418 [hpmuseum.org]
My Dad had one and knew of a similar problem where it would return incorrect results for amortization calculations for smaller values, but I don’t remember the cut-off was, as it was probably 30+ years ago
(Score: 2) by driverless on Friday September 20 2024, @10:01AM
Hey, could have been worse, if it was a Middle-East model it could have exploded while he was using it.
(Too soon?).
(Score: 2) by VLM on Thursday September 19 2024, @11:36AM
I find it odd that the acknowledgements at the end of the blogvertisement advertise the DM42, which is admittedly a great calculator, instead of advertising the DM12 which you can see at
https://www.swissmicros.com/product/dm12 [swissmicros.com]
I own a DM16L, a PX16C, have an emulator for the -16 on my phone, etc. The hardware is much faster and easier to use than my phone but if I'm away from my desk its nice to have.
Every decade or so I get a yearning to mess around with classic DEC stuff and then I appreciate having an easy way to convert between octal and everything else. IIRC, which I may not, the original 8080 was an octal architecture when you look at machine language opcodes and binaries, and its numerous successors moved away from being octal and just rammed stuff in there until it fit.