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Does anybody have the HP42s ROM in file format?
Also if anybody has the ROM for the HP41CV emulator card for the HP48SX that would be useful as well (would buy it
if anybody against all odds would have it for sale...)

I would also find it interesting to hear how far people
out there have progressed on emulating the HP42s...

Erik Ehrling

I would appreciate it if you wouldn't request copies of copyrighted materials on this forum. (Out of production doesn't mean no longer copyrighted.)

I apologise, it was not my intention to post an illegal request. However, my main question remains unanswered. I see a lack in emulation software in that there are full-fledged emulators for both the HP41, HP48 and HP49, but not any decent emulator for the HP42s. As a first step to understanding of the internal workings of the HP42s I would like to try to disassemble the ROM and therefore I would like to have a copy of it on my PC. If I am left with no other option I could always use the built-in monitor to browse it and type it in by hand, line by line, but I would prefer using the IR-port to transfer it either to a HP48GX or directly to an IRdA port.

I saw some postings about someone trying to disassemble the ROM and therefore assumed that someone had succeeded in transfering it.

I certainly understand if HP wants to retain the copyright for the HP42s. My personal hope is that they would put in full-scale production again. ("Do not change a winning concept")


Yes, it is possible to download the HP42S ROM to PC, with the help of a HP48. (I did it twice, for two different versions of the HP42S). Of course, I can't post the ROMs (copyright issues), but I can expain how I did. I used the built-in monitor of the HP42S and the 'COS' key that send a line of codes to the IR that can be received by the HP48 with the HP INPRT utility. Of course, the process is quite long (a few hours).
And yes, I'm thinking about writing a HP42S emulator!
I already wrote emulators for the HP41 and HP71 (I think that it's the only HP71 emulator, except perhaps the one used by HP).