HP Forum Archive 21

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HP42S ROM question Message #1 Posted by Han on 1 Oct 2012, 9:44 a.m. For those who have access to the ROM source or a disassembly of the ROM: There are many blocks of RPL that do not seem to be enclosed in the typical :: ; (DOCOL and SEMI) environment, and are preceded by 4 nibbles. Does anyone know what these four nibbles stand for? Are they similar to library objects in the HP48 (2 nibbles for library number, 2 nibbles for library commands)? I am trying to picture the ROM as if it were the predecessor to the HP48 ROM, and this is my best guess. If you know more, I would love to hear about it. Han

Re: HP42S ROM question Message #2 Posted by Raymond Del Tondo on 1 Oct 2012, 11:07 a.m., in response to message #1 by Han You could use the Emu42 debugger, set the trigger on access of one or more of those nibs preceeding certain RPL code, and see which routine it's called from;-) I didn't do it so far, but my guess would go into an XROM direction, or maybe it's kinda property field for mathematical functions, like in the HP-48 . Did you check the XROM table at the end of the ROM?

Re: HP42S ROM question Message #3 Posted by Han on 1 Oct 2012, 3:15 p.m., in response to message #2 by Raymond Del Tondo Quote: You could use the Emu42 debugger, set the trigger on access of one or more of those nibs preceeding certain RPL code, and see which routine it's called from;-) I didn't do it so far, but my guess would go into an XROM direction, or maybe it's kinda property field for mathematical functions, like in the HP-48 . Did you check the XROM table at the end of the ROM? I did not think to check, but I'll do that. Thank you for some really good ideas.

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