HP 86: Strange Error

[Martin Hepperle]

(11-19-2017 12:07 AM)Michael Fehlhammer Wrote:  My newly acquired HP 86A displays a strange warning immediately after power on:
Warning 27: 85 ROM disabled.
Needless to say that I didn't plug in an HP 85 ROM. I tested without any module plugged in.
I wrote a short BASIC program, so far the machine seems to work fine.
Does anybody has an idea what could be the reason for the strange warning?

Michael,

first I would check which ROMs are visible to the machine. My SYSINVentory program (see groups.io) should list all ROMs found on the machine.

Maybe one of the internal System ROMs has a flaw. You could write a BASIC program to read the content of each system ROM (using a PEEK() BPGM), dump the content to a file and then compare with known good ROM images, e.g. from Everett's Series-80 Simulator or a dump your second machine.
If only the checksum byte in a ROM is wrong: no problem. Otherwise you can identify which BASIC function is affected by comparing the location of the error in the ROM with the source code disassembly.

Martin