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HP42S ROM question


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Post: #2
10-01-2012, 09:44 AM
Han Offline
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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

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Post: #3
10-01-2012, 11:07 AM
Raymond Del Tondo Offline
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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?

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Post: #4
10-01-2012, 03:15 PM
Han Offline
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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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