Reading HP67 ROMs

[teenix]

(06-25-2022 10:57 PM)Marcovecchio Wrote:  This is great progress! I'm sure this will help diagnose ROM condition very easily.

Also, fully understanding how each ROM chip interfaces externally, will help building replacements. I know there are the whole board replacements, but it's interesting to be able to replace each one individually.

Eduardo

I have the ROMs mostly figured out. I just have to play with a few more and I should have the secrets I need. They operate slightly different across the models.

I have written the code to read and write the RAM inside the ROM chips but need to double check the code output because the IC could be damaged if not done correctly due to bus conflicts.

I have looked into individual ROM replacements and I don't think it is that hard once one understands how the internals work. Once I have it working good enough I will publish what I find.

cheers

Tony