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I have an HP41CV with a math I module and advantage module. I noticed that the order of placement of the modules make a differance as to whether they work together or not. Is there a conflict in having both modules installed simultaneously? I noticed they have some similar capabilities but some individual as well. For instance I could not run the SOLVE function (from math I) when it is placed after the advantage module with an error, NONEXISTANT. Just curious if I have missed something here
having not read all the manuals.


I figured this out. Read the manual, looks like these pacs do conflict with each other, the advantage pac is more capable so I will probably put the math pac out to bid on ebay.


I quote from the HP-41 ADVANTAGE manual p16.

"Certain function names used by the HP-41 Advantage are also used by the HP-41 Math Pac and the HP-41 Real Estate Pac. When using these functions you should remove the module whose functions you do not want accessed."

For the Math Pac the functions listed are;

All complex number functions and all functions in DIFEQ.

Hope this helps.

BTW there is a conflict with the HP-IL Development module such that the manual recomends that the two modules must not be plugged in at the same time. They share the same id numbers.

Yes there are a number of other functions shared by the 2 pacs besides complex number functions and all functions in DIFEQ which are not mentioned in the manual.


If you _need_ to use functions from both modules in a
program, and you reach a program step where you want
to enter the name of a function which exists in _both_
modules, then:

Turn the HP-41 off.
Take out one of the modules - keep only the one
whose function you want plugged in.
Turn the HP-41 back on, enter program mode, put
the function you want into the program. Since only
one module is plugged in, there is no conflict.
Now you can carry on entering the program. When you
need to, turn the HP-41 off and put in the other

Although the function _names_ are the same, the
program steps actually contain an XROM command,
which will be different, depending on which module
was plugged in when the program step was entered.
When you run the program, both modules can be plugged
in and the program will still work.

Things are less clear-cut if you try to execute a
function whose name is in both modules, from the
keyboard - the function is picked from the module
in the lower-numbered port. To override this, assign
the function to a USER mode key, with only the module
you want plugged in. The command will then work when
you press that key even if both modules are later
plugged in.

The worst-case scenarion is where different functions
have the same XROM number! But that's a different topic.

Keep those HP-41s working!

Wlodek Mier-Jedrzejowicz

Of course you could use synthetic programming to enter the xrom code directly into your programme!