Undocumented HP-41 Coconut opcodes


Sometime ago, it was reported some undocumented opcodes like GO->XQ, ?OFF, POWON, ?WKUP, KEYS=C that are supposed to be used in the HP-41 internal Master Control Program. For instance, a description is found in the english edition of J-D Dodin's book "Inside the HP-41".

Having received my Datafile archive CD from Jake Schwartz a few days ago, I came accross the original description of these instructions as published in Datafile V3N2p15 under the "April Column" by Bill Reggusy, who was supposed to have made his discovery on his HP-41C SN 2321S010484 (!).

Do you see now where I want to come to?

Actually Bill Reggusy wrote a small note in Datafile later to make clear for everybody that it was just a hoax. The funny thing is that it this hoax was seriously reproduced in a book, and maybe in some other publications.

I must admit I thought to support these opcodes in my Emu41...



Although I never planned to support these opcodes in HP-41X, this is very nice from you to make it clear it was a hoax :-)



Hello JF!

Tnx for the info. Following a part from my NutEm in FORTRAN with the opcodes I did not need up to now (2 are for the timer).

entry hpc001                  
entry hpc098
entry hpc09a
entry hpc09b
entry hpc09c
entry hpc09d
entry hpc09e
entry hpc09f
entry hpc0c8
entry hpc0ca
entry PFB0A9
entry PFB0E5
write(6, '(A, 3(z2, 1x), z4)')
call sysabd(1)


Edited: 4 Oct 2004, 5:01 a.m.

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