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HP-41CX w/ XF-Module - just curious
07-26-2019, 04:36 AM
Post: #17
RE: HP-41CX w/ XF-Module - just curious
The BUS search order is dictated by the mainframe MCODE. It always starts at page 5, moving up until page F. When the CX was released HP added a new page at the END of the search, page #3 - that's why 3 in the CAT 2 is shows the last.

So when you XEQ EMROOM, the OS finds the XROM #26 first corresponding to the external X-Funct module. It scans that FAT and notices that the id# in question is not there, so it puts out NONEXISTENT - without continuing the search along the BUS and threfore never reaching page #3 (the "last" one).

The same happens if you plug two different modules with the same XROM id#, and the first one has fewer functions than the second: only functions from the first one are found.

It's all in the MCODE ;-)


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RE: HP-41CX w/ XF-Module - just curious - Ángel Martin - 07-26-2019 04:36 AM

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