HP Forum Archive 08

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Hp-41 execution redirection Message #1 Posted by Rick Garza on 4 July 2002, 8:58 p.m. I am trying to understand how the hp-41c transfers execution control if it sees a diagnostic module installed at page 4. Is the Instruction Addressing hardware redirected within the cpu? Or is it just a jump to page 4 and all the instructions within that rom are hardcoded to page4 and above(an absolute code segment)? I'd appreciate it if any gurus out there still can answer this one since I dont have a copy of the service module. I understand it was for hp internal use only...... Regards

Re: Hp-41 execution redirection Message #2 Posted by HrastProgrammer on 5 July 2002, 12:47 a.m., in response to message #1 by Rick Garza At the addresses #0180 and #01AD in the HP-41 ROM there is a GSUBNC #4000 instruction. If the diagnostic module exists then execution is transferred to the address #4000. If it doesn't exists then a simple return occurs (this is a nice feature of the Nut CPU).

Re: Hp-41 execution redirection Message #3 Posted by HrastProgrammer on 5 July 2002, 12:52 a.m., in response to message #2 by HrastProgrammer Forgot to say: the diagnostic module is tested every time when waking up from light or deep sleep.

Re: Hp-41 execution redirection Message #4 Posted by J-F Garnier on 5 July 2002, 11:50 a.m., in response to message #2 by HrastProgrammer To be more precise, the gosub is even not executed if the target address is empty (0). On Saturn processor (HP71B..HP49G), the 0 opcode (RTNXM: return and set external module missing) provides the same kind of function. J-F [Hello HarstProg!]

Re: Hp-41 execution redirection Message #5 Posted by HrastProgrammer on 7 July 2002, 2:43 a.m., in response to message #4 by J-F Garnier Thanks for the correction, J-F :-) How do you do? Are you still working on Emu42?

Re: Hp-41 execution redirection Message #6 Posted by Mike (Stgt) on 8 July 2002, 11:10 a.m., in response to message #1 by Rick Garza There once was a paper from PPC about MCode, in addition a listing of the service module SM-1:C. With a ZENROM and an MLDL or adequate you may type in the 4k. Or much easier with one of the 41-emulators (from W. Fulrow, J-F Garnier, HrastProgrammer or mine if you have access to VM/ESA). Then you may use your favoured editor and make a BIN from that listing. ;-) Hello J-F and Hrast! After several month out of 41-business I'm about to update my site at compuserve. Could you pls sent me your valid URL for the latest revision of your emulators? TIA. Ciao.....Mike

Re: Hp-41 execution redirection Message #7 Posted by HrastProgrammer on 9 July 2002, 1:40 a.m., in response to message #6 by Mike (Stgt) Hi Mike ... nice to see you ... My homepage is <http://hrastprogrammer.tripod.com>. It was updated before a month or so with the latest info about HP-41X Extended MicroCode Emulator for HP-48GX and HP-49G.

Re: Hp-41 execution redirection Message #8 Posted by Mike (Stgt) on 10 July 2002, 11:30 a.m., in response to message #7 by HrastProgrammer Hello! Sorry to appear only infrequent on this list. I was monopolized by my HP200LX. I just try to 'finish' my Coconut emulator "NutEm". Still looking for a way to migrate FORTRAN to an other platform. Ciao.....Mike

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