I wrote a little program that reads HP-41 ROM images, extracts the user code from them, and converts it to *.raw files you can import into Free42 or Emu42 (or HP-42X, I expect, or even into any HP-41 emulator).
It converts XROMs that point to user code within the same ROM to corresponding XEQ commands; it converts strings from HP-41 to 42S encoding; it emits warnings about XROMs that point to machine code functions, and about XROMs that are not local to the ROM in question and do not match HP-42S instructions either; and finally, it warns when it finds any synthetic code (most of which won't work on the 42S, at least not the really neat stuff).
The ROM image must be in *.ROM format, meaning: each 10-bit word is encoded by a byte which has bits 9-8 in its bits 1-0, followed by a byte containing bits 7-0. A normal 4k-word ROM thus comes in an 8kbyte file. If you have only *.MOD format images, Warren Furlow has a program called MODFile on his site (TOS) that extracts the *.ROM files from a *.MOD file.
It's called rom2raw and you can download it from my web site. The download is a zip file that includes the source code and a Windows console executable.
Enjoy!
- Thomas
Edited: 8 Feb 2006, 5:04 p.m.