HP 12C+ Firmware

[dvcirilo]

Hello all,

Following multiple threads here I was able to repurpose my HP 12C+ (originally with 2008 firmware and SST bug) into a HP 15C with extended memory and all.

Now comes the problem that I'd like to bring it back to its 12C origins, but the only firmware I found (HP12C+_12-12-2011.bin) here does not seem to work with my version of the hardware. There is permanent minus sign on screen, and some buttons seem to have switched positions, as the "g", that lights the "G" (close to RAD) on display, the "f" lights the BEGIN, and so on.

I have flashed this multiple times, back and forth between the 15C firmware, which works flawlessly and this 2011 12C+, which does not work, probably ruling out any hardware defects.

Does anyone happen to have the 2009 versions of the hp 12C+? From my research here, it seems that last 2009 version is from 2009-11-19.

Thanks!!

[Mark H. Shin]

The HP-12C+ firmware is contained in the HP12C+ SDK, which can be downloaded from link provided by original post

It is within the folder hierarchy: AT91SAM7L\ewp\12C\Exe\HP12C+.bin

[dvcirilo]

Thanks, I have tried this one, but it does not work, doesn't even turn on.

The HP12C+_12-12-2011 version kindly posted by Katie here, which gives me the weird behavior, minus sign always on, "f" and "g" keys not working, etc. Basic operations work ok.

I'm looking for either the 2009-11-19 or 2009-07-24 versions, as cited here.

Originally this 12C had the 2008-06-28 version.

I reverted back to the 15C firmware. Maybe its fate now is to live as 15C forever.
I'm better looking for a keyboard overlay.

[Stevetuc]

(08-24-2023 01:40 AM)dvcirilo Wrote:  Thanks, I have tried this one, but it does not work, doesn't even turn on.

The HP12C+_12-12-2011 version kindly posted by Katie here, which gives me the weird behavior, minus sign always on, "f" and "g" keys not working, etc. Basic operations work ok.

I'm looking for either the 2009-11-19 or 2009-07-24 versions, as cited here.

Originally this 12C had the 2008-06-28 version.

I reverted back to the 15C firmware. Maybe its fate now is to live as 15C forever.
I'm better looking for a keyboard overlay.

Perhaps try this rom
HP-12C+_Jose.bin
Jose from Calculatorstore sent me this as the latest rom for the older HP12C+
He mentions here New flashing service that he successfully flashed this onto the HP12C+ older version (pre 2015)

I have checked the file with a hex editor and the original firmware is embedded in 16bit bigendian at hex offsets 5034-8F31.
The files you had trouble with I am unable to find the original firmware embedded within which may (or may not ) explain the problems you had.

I'll post a bit more later regarding finding the embedded firmwares within both the HP12C+ and HP15C+ (LE) firmwares that are available via other posts on this forum.

[brouhaha]

(05-25-2024 09:39 AM)Stevetuc Wrote:  The files you had trouble with I am unable to find the original firmware embedded within

I think those firmware versions had the Nut code expanded inline into sequences of ARM code, in order to speed things up by avoiding an outer interpreter lfetch and decoee loop. In the early 1990s I did something similar with an experimental version of my Atari vector game simulator.

Since HP went back to having a Nut ROM image, perhaps the performac3 gain was not as much as they expected.

[Earle Grey]

(08-24-2023 01:40 AM)dvcirilo Wrote:  Thanks, I have tried this one, but it does not work, doesn't even turn on.
....<snip>....
I reverted back to the 15C firmware. Maybe its fate now is to live as 15C forever.
I'm better looking for a keyboard overlay.

Hello dvcirilo!
I hope you don't mind me sticking my nose into your thread, but I had an idea for you. Now I totally understand the fun of hobby modifications, but it sounds like you've flashed your way into a one-way street (or maybe a blind alley) and gotten stuck. Yes, you may be stuck with a 15c, but that's not such a bad thing — unless you wanted to gift your 12c along to someone who needs the unique 12c functions and key layout, etc. You may not want to give them a "crossdressing" 15c !

So there is an easy solution, albeit an unorthodox one for a hobbyist like you. But you can grit your teeth, keep your modded 15c, and just buy a brand new 12c. Either from the licensed reseller (Royal, or HP Office Supply in the US) at list price of $70, or from an auction site where I saw a new one listed for $30 yesterday. (I, too, am considering a gift to a friend, which is why I was looking around, and the price seems nominal to me.)

Well. if you're wanting to restore the 12c you have just for kicks, I get that, too, so please take no offense. I just know sometimes I get fixated on doing something and don't see a simple & cheap solution staring me in the face!

—Earle.

[dvcirilo]

(05-25-2024 09:39 AM)Stevetuc Wrote:  Perhaps try this rom
HP-12C+_Jose.bin
Jose from Calculatorstore sent me this as the latest rom for the older HP12C+
He mentions here New flashing service that he successfully flashed this onto the HP12C+ older version (pre 2015)

I have tried it and can confirm it does work! Thank you!

It shows as checksum 2424h and version 2009-11-19.

I have done limited testing, but it seems to be all functional.

[dvcirilo]

(05-25-2024 11:11 PM)Earle Grey Wrote:  Well. if you're wanting to restore the 12c you have just for kicks, I get that, too, so please take no offense. I just know sometimes I get fixated on doing something and don't see a simple & cheap solution staring me in the face!

Thanks for the suggestion, I have a few other 12C/12C+ laying around, and really didn't mind having an extra 15C.

The interest in finding a "working" firmware was mainly for the completeness of the modding experiment, being able to go back and forth between 12C/15C, and even recover from temporary/unsuccessful experiments with the devkit.

I would feel bad for "bricking" a calculator, even if it's cheap to replace.

[dm319]

This thread is very interesting - I didn't know there was such a thing as cross dressing HP-12c's ?. I've been testing the tvm abilities of various financial calculators, and I'm wondering if these ROMs would give different results.

[Steve Simpkin]

(05-27-2024 08:43 AM)dm319 Wrote:  This thread is very interesting - I didn't know there was such a thing as cross dressing HP-12c's ?. I've been testing the tvm abilities of various financial calculators, and I'm wondering if these ROMs would give different results.

AFAIK, All 14+ hardware versions of the "HP-12C" (not counting the HP 12C Platinum) are running the exact same code base as the original HP-12C released in 1981. From 1981 to 2008, that code ran on a hardware variation of the original "Nut" processor. Starting in 2008, they have used an emulation of the Nut via ARM. In any case, they are still using the same code base developed in 1980 (the earliest S/N HP-12C known). As such, they should all produce the exact same calculation results.

The HP 12C Platinum is a reimplementation of the HP-12C functionality (with enhancements) using completely new source code. It runs on a variation of the 6502 processor.

See the following post forum more information on the variations of the HP-12C.
https://www.hpmuseum.org/forum/post-46064.html

[dm319]

(05-27-2024 12:18 PM)Steve Simpkin Wrote:  AFAIK, All 9+ hardware versions of the "HP-12C" (not counting the HP 12C Platinum) are running the exact same code base as the original HP-12C released in 1981.

The HP 12C Platinum is a reimplementation of the HP-12C functionality (with enhancements) using completely new source code. It runs on a variation of the 6502 processor.

Ah phew. Looking at that page and the number of variants I am glad I don't need to test them all! The HP-12c platinum seems to beat the HP-12c in every category with the TVM problems I've thrown at it by a couple digits on average:

Code:

| calculator     | year  | 1   | 1b  | 2   | 3   | 4   | 5   | 6   | 7   | 8   | 9   | 10  |
|----------------|-------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|
| HP-12cp        | 2003  | -8  | -10 | -6  | -6  | -10 | ERR | ERR | -21 | -11 | 0   | 0   |
| HP-12c⁴        | 1981  | -6  | -8  | -4  | -4  | -8  | ERR | ERR | -9  | -11 | 3   | 2   |

ref here.

[dm319]

There looks to be another ROM out in the wild. It looks like it can be identified by not being able to change dots to commas and vice versa.

See this Reddit thread : https://www.reddit.com/r/hpcalc/comments...?context=3

I will add this 12c to my results.

[dm319]

These are the results of this newer HP-12c. These results [dramatic music] have never been seen before in an HP financial calculator. It is able to solve problems 5 and 6, which no other HP calculator can do. But it fails on problem 4, for which we've been able to get an answer from at least the HP-70 onwards. It also fails on problem 7, for which the HP-12c platinum was one of the most accurate at calculating. There is also a very disappointing result for problem 3, which isn't a solving for i problem, but solving for FV with a very high N. It also gives the most accurate result for problems 9 and 10 out of the three of them.

So what do we think? If this is genuinely new firmware for the HP-12c then they've completely reimplemented the code with a new 'solve for i' solver which fails at values of i close to 0, but is able to return a result for problems with multiple solutions.

accuracy rankings (-1 = accurate to 1DP, lower is better):

Code:

| calculator    | year  | ref    | 1   | 1b  | 2   | 3   | 4   | 5   | 6   | 7   | 8   | 9   | 10  |
|---------------|-------|--------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|
| HP-12cp       | 2003  |        | -8  | -10 | -6  | -6  | -10 | ERR | ERR | -21 | -11 | 0   | 1   |
| HP-12c comma  | ?2022 | 11     | -6  | -9  | -6  | 0   | ERR | -8  | -8  | ERR | -11 | 0   | 0   |
| HP-12c        | 1981  | 8      | -6  | -8  | -4  | -4  | -8  | ERR | ERR | -9  | -11 | 3   | 2   |

results:

Code:

| calculator      | 1                                    | 1b                                    | 2                                    |
|-----------------|--------------------------------------|---------------------------------------|--------------------------------------|
| HP-12c          | -1368.148355                         | 4.37321837                            | 6803.092172                          |
| HP-12cp         | -1368.14835535                       | 4.3732183723                          | 6803.092162                          |
| HP-12c comma    | -1368.148355                         | 4.373218372                           | 6803.092162                          |
  
| calculator       | 3                                    | 4                                       |
|------------------|--------------------------------------|-----------------------------------------|
| HP-12c           | 331667.0067                          | -7.983367984e-10                        |
| HP-12cp          | 331667.006691                        | -7.98336798336e-12                      |
| HP-12c comma     | 331666.9849                          | ERR                                     |

| calculator      | 5                                   | 5A                                   | 5B                                   |
|-----------------|-------------------------------------|--------------------------------------|--------------------------------------|
| HP-12c          | ERR                                 | ERR                                  | ERR                                  |
| HP-12cp         | ERR                                 | ERR                                  | ERR                                  |
| HP-12c comma    | 14.43587133                         | 14.43587133                          | ERR                                  |

| calculator      | 6                                    | 6A                                   | 6B                                    |
|-----------------|--------------------------------------|--------------------------------------|---------------------------------------|
| HP-12c          | ERR                                  | ERR                                  | ERR                                   |
| HP-12cp         | ERR                                  | ERR                                  | ERR                                   |
| HP-12 comma     | 58.46195527                          | 58.46195527                          | ERR                                   |

| calculator      | 7                                        | 8                                      |
|-----------------|------------------------------------------|----------------------------------------|
| HP-12c          | 2.181818182e-10                          | 3.125004736e-6                         |
| HP-12cp         | 2.18181818182e-10                        | 3.125001e-6                            |
| HP-12c comma    | ERR                                      | 3.125001e-6                            |

| calculator      | 9                                    | 10                                   |
|-----------------|--------------------------------------|--------------------------------------|
| HP-12c          | 1041                                 | 1052                                 |
| HP-12cp         | 1061                                 | 1076                                 |
| HP-12c comma    | 1061                                 | 1077                                 |

problems are found here.