HP 41 Diagnostic & Service ROM

[Don Williams]

So I finally completed my New Years resolution to examine 5 decrepit HP 41's I had acquired over the years. On first examination I determined they were only fit as parts machines. It was obvious that the prior owners were chasing a zebra strip problem with a soldering iron. However, I was lucky, and now all 5 are alive again, except for one bad keyboard on a CX.

But that does not mean they don't still have hidden flaws. Unfortunately I don't have a service or diagnostic ROM, and I would feel more comfortable if I could run those tests.

Hence my question.

Does anyone have a listing of the service or diagnostic ROM's.

I have loaded the MOD files in a virtual HP 41, but they are "takeover" ROM's so you cannot examine the subroutine code.

Am I naive to believe these are nothing but clever focal programs written by HP experts to exercise the HP 41 hardware?

Could these ROM's contain additional circuits needed for that purpose?

If they are just software, with a mechanism to autoload on startup and remap the keyboard, then it might be possible to extract the subroutines and publish them. Or perhaps there is already a listing somewhere that I haven't found.

I don't have the hardware (clonix, MDL etc.) to accomplish this task, but someone else might. In fact it may have already been done.

Anyone with the expertise to advise me on this project?