The Rogue HP-12c

[dm319]

(09-12-2024 12:13 AM)brouhaha Wrote:  If so, you should be able to dump the firmware using the cable from The Calculator Store, and SAM-BA.

Very tempted to do this!

(09-12-2024 12:05 PM)Steve Simpkin Wrote:  I believe the HP-12C platinum models use the Sunplus SPLB20D2 (earlier) or Generalplus GPLB31A 6502-based CPU with original code running natively on that processor (no emulation).
https://en.wikipedia.org/wiki/HP-12C#HP_.../_Prestige
http://www.brouhaha.com/~eric/hpcalc/voy...iants.html

Yes, not quite what I meant! I think I phrased it badly - don't really mean emulation - I think Saturn simulation is probably a better word. I'm going to quote you to you now:

(07-05-2024 06:56 PM)Steve Simpkin Wrote:  I recall Cyrille De Brébisson mentioning that they had recreated the Saturn math library in C for use in their more modern calculators that did not use Saturn emulation like the HP 39gII and the HP Prime. I believe that Home mode on the HP Prime utilizes this library which is why it has the same forensic results as Saturn-based models.

Edit: Here is a reference from Cyrille mentioning the recreating of the math library.
https://www.hpmuseum.org/forum/thread-14...#pid124770

On the forensic results, the Hp17B/17BII+, 20b, 30b, 50g, 17BII etc etc return pretty much identical results. The HP-12cp often does too, but there are some interesting exceptions - like returning only the integer for solve-for-N, like the 12c.

(09-12-2024 01:50 PM)AnnoyedOne Wrote:  I'll try and explain this as simply as I can. It may be longish. Again I did this stuff, professionally, for decades.

As you know, I have zero career knowledge of these things - so do go slowly.

(09-12-2024 01:50 PM)AnnoyedOne Wrote:  To my knowledge the HP-12C Platinum firmware was completely rewritten and is not a NUT emulation like the HP-12C+ or DM12L. I think the code was mostly written in 'C' (likely with some assembler). Again a complete rewrite that acts similarly to the HP-12C (but not identically).

No, I didn't think it was NUT emulation and I don't think I was saying that. Please see reply above re: the Saturn maths library, which I guess 'simulates'(?) the behaviour on the original Saturn hardware.

So I've hinted at this before, but I'm going to outright say it. The idea that the HP-12c platinum was some kind of blind re-write using not much more than some technical specs and the user manual for the 12c can't be right.

The forensic tests return the exact same results as the other Saturn financials, to the same degree of digit accuracy, except for a couple of exceptions. One exception is the result for puzzle 7, where it is remarkably similar to the regular 12c, and performs better than any Saturn machine. The other is the integer return on the solve-for-N, again something that only the 12c does.

I don't know what went on, but I simply don't believe the idea that Kinpo acquired a decade of HP TVM refinements and knowledge, to code their own TVM solver that essentially knocks it out the park, but also suspiciously behaved very much like a cross between the 12c and the Saturn machines.

(09-12-2024 01:50 PM)AnnoyedOne Wrote:  The unknown firmware in dm319's HP-12C has a 16-bit checksum just like the Platinum/Prestige models. My theory is that although the hardware is ATSAM2LC2CA based (modified) GPLB31A code was recompiled to produce the firmware. Perhaps bugs were introduced by this process. By whom? I've no idea and we'll probably never know.

Ok this is very interesting. This suggests the code in this 12c is running natively then, and not running on a NUT emulator?

(09-12-2024 01:50 PM)AnnoyedOne Wrote:  Perhaps bugs were introduced by this process.

I feel like I'm repeating myself but this isn't a bug. You don't accidentality introduce an entirely re-implemented solver. Oh whoops, I coded a whole new solve-for-i algorithm just before I hit re-compile! All I meant to do was remove the algebraic mode, but look what I've gone and done!

(09-12-2024 01:50 PM)AnnoyedOne Wrote:  This is why I asked (and got no answer) if the HP-12C in question had any hidden Platinum/Prestige functionality. If so that would tend the confirm my theory (left over and unremoved code--but no Platinum keyboard markings or LCD annunciators).

Happy to try these out for you, but was unsure what you meant.

The rogue HP-12c does not enable stack lift after inputting values into the TVM, I believe this is standard 12c behaviour (though I don't have a regular 12c, just this weird one), but it is not standard platinum behaviour, which enables stack lift after inputting data.

(09-12-2024 01:50 PM)AnnoyedOne Wrote:  One easy test is 2, ENTER, g+X [x^2]. On a Platinum/Prestige you'd get 4 (2 squared). On a HP-12C nothing would happen (no g+X [x^2] function).

If I do 2 g+X on the platinum I get 4, on the rogue 12c I get 2 x whatever was in x before.

(09-12-2024 01:50 PM)AnnoyedOne Wrote:  The point of all this is that one must be a detective and have some idea what to check for. Physical features (from photo's, inspection) can provide clues but won't tell you everything.

Everything's a clue really... if you have suggestions, I am all ears.

Do you know how to check the firmware of the HP-12c platinum? I tried doing the same on the 12cp as the 12c, but it went very strange - each key press kept filling in another segment of the display and I couldn't fix it without resetting.