HP-15C expanded memory firmware: problems with matrix larger than 8x8

[brouhaha]

(07-03-2024 09:32 AM)Giorgio Wrote:  I wanted to try this patch to generate an Error 11, but I noted a discrepancy.
The original data (before patching) should be 000 at addresses 13F9-13FD, but I found different data in the original ROM:

13F9:08B
13FA:0E5
13FB:2D3
13FC:2C6
13FD:0F5

Did I miss something?

Those value are most definitely not from an "original" 15C ROM. Those contents were in the modified 15C ROM distributed with Nonpareil until two years ago, which bears my copyright, is not open-source, and is not authorized for use in anything other than Nonpareil.

I suggest you get a proper dump of the original 15C ROM. One can be found in the Nonpareil github repository.

If you can't use the true original HP-15C ROM, for instance, if you're trying to use it on modern hardware that requires a modified ROM, then it should be OK to make the patch even though those five locations were not zero.