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Full Version: HP 41CV – CLP After Initialized ROM Program
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Thanks for the patience with what may be an elementary question, I just can’t seem to find the answer in the manuals.

I have recently started to work with HP-41 modules.

When you initialize a program from a ROM (in this case I am working with the Real Estate Pac and I am initializing the Compound Interest program with XEQ ALPHA $ ALPHA), it seems to copy the program to the main memory.

Is this the case or the correct understanding of what is happening?

From this point though, I have attempted to clear the memory (for instance, to manually enter a new program) by executing CPL ALPHA ALPHA. This returns the error message “ROM”. It is clear from the manual that the “ROM” error is from an attempt to modify a program in an application module.

I have only been able to clear the memory by manually clearing with ON and CLX.

Would someone be able to describe, or point me to another topic or resource, how memory works when using application pacs?


When running (XEQ) a ROM Pac program, it is not copied into the user RAM, but executed directly from the ROM module.

You can use the "COPY" command and save a copy of that program into the RAM instead. Then you can even remove the module (provided there are no other dependencies) and execute this program from RAM.

If you later want to remove it from RAM just use CLP as needed.

On the procedure you've described your program runs directly from the ROM Pac; hence when you try to use CLP you receive the error message: "ROM".

Hope this helps.

Best regards.

Hi Diego,

Thank you and this is helpful.

With this advice and some experimenting a bit more, I think I may have be getting a handle on it.

Thanks again!
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