Can the HP-12C's program memory be upgraded?

[lvt]

(11-21-2023 06:37 AM)brouhaha Wrote:  

(11-21-2023 04:07 AM)lvt Wrote:  I would like to know whether it's possible to upgrade the 12C's memory, just like with the 15C?

I did the early patching to expand the 15C memory back in 2004, then Hrast Programmer and J-F Garnier developed additonal patches necessary to make the expanded memory work correctly with the complex stack, SOLVE, and INTEGRATE. Our patches are present (uncredited) in both the 15C CE and the expanded-memory versions of the Swiss Micros DM-15, along with other patches HP and SwissMicros made for various reasons. One of the additional patches SwissMicros made was to allow the pool to start at an arbitrary register, rather than having to be a multiple of 16, which I didn't personally think was worth the additional effort and testing. That gives the DM-15 user five additional registers over our patches.

Although the HP-12C models made starting in 2008 and 2015, and the SwissMicros DM-15 and DM-15L are flash upgradeable, upgrading the 12C (or 10C) microcode to provide additional memory is MUCH more difficult than doing that to the 15C and 16C microcode. This is because the HP microcode was specifically desgined for exactly 99 steps (79 for 10C), whiel the 15C and 16C microcode was in most regards fairly memory-size-agnostic. Increasing the 12C memory will take a huge amount of modification to the microcode, rather than just a few minor patches.

The reason the 12C Platinum and 12C Prestige are able to have more steps of program memory is because they have an entirely new code base, not derived from the original 12C microcode. The 12C Platinum and 12C Presige units made up until now (or recently) are not flash upgradeable, but it is expected that such capability will be added in the not-too-distant future.

Adding additional program memory to the 12C is on my to-do list, along with scientific functions and many other enhancements to the 12C microcode. I started early this year with enhancing the 16C microcode, because it was somewhat easier than doing it to the 12C, and gave me some experience with some of the things I want to do on the 12C. I'm not entirely done with the 16C enhancements, but have written up some of my findings in another thread in the forum, and also gave a brief talk about it at HHC 2023.

Unfortunately I don't expect to have enhanced 12C microcode ready to show or distribute any time soon, because I've got a lot of other higher-priority calculator work on my plate, including a new (perhaps final) release of Nonpareil, and development of Nonpareil 2.

Of course, I'm not the only person here who knows how to hack HP calculator microcode, so someone else might beat me to it!

Thanks a lot, I'm glad to know that it's technically possible.