HP 41CX/Swiss Micros DM41X and XROM

[Sylvain Cote]

To be more precise, when you type XEQ "TANH", the 41OS first search for that function internally, then go over each modules and when found insert the ROM ID and the Function table location in a 2 bytes entry in the HP-41.
Now if you remove the module and insert another module who has the same ROM ID (01) and has has least 36 functions, the 41 will call that function whatever it is called, like LBL "BOOM" (ID=35) of "GAME9" ROM (ID=1) [just in case, that ROM does not exist]
Sylvain

PS: The 2 bytes entry is defined like this: XROM preamble (22 or 10110) followed by the ROM-ID (0..31 or 00000..11111) followed by the FNC-ID (0..63 or 000000..111111).
So in this case

Code:

TANH function (ID=35) of the Math  ROM (ID=01) gives: 22 01 35 → 10110 00001 100011 → 10110000 01100011 → A0 63
BOOM function (ID=35) of the GAME9 ROM (ID=01) gives: 22 01 35 → 10110 00001 100011 → 10110000 01100011 → A0 63

Edit: Arrgg, I started to reply at 9h45, something happened, finally I post it 2h later and for sure Robert answered that one long before me.