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I have a Prototype version Advantage Rom Module for HP41 series calcs that I thinking about selling but I don't have an idea what it might be worth. It's fully functional as far as I can tell. There are no numbers or dates stamped on the rom case, just a sticker indicating what it is. No documentation is included.

I see one listed on ebay for $190 but since mine is a pre-production model it might be worth.

Any ideas?

Show us some pictures!

Maybe you should give us more informations:

* Why do you think it's a prototype?
* What are the differneces between the normal version and yours in detail?
* What does CAT2 sais? (there are two versions available "-ADV CONV A" and "-ADV CONV B".

For a regular Advantage pac I would say that a price of $40-50 would be adequately. I bought my two versions for about $50 each, boxed, with manuals.


Hi Matthias,

Why do I think it's a prototype? There are no official HP numbers or country of origin markings on it. There is only a dot-matrix printed sticker affixed in the identification area that says "ADVANTAGE PROTOTYPE".

I'd post some pics but I don't have a site to host them from. I've contacted the curator here to post them in the guest folder.
As soon as the happen I'll submit another post with pics.


41CV cat2 list the entire catalog, there are over 100 functions/routines, too many to list here. I'll try to compare the list to the manuals to see if there is a difference.

Thanks for the reply,

A Covallis Division employee once told me a tidbit of the history of the Advantage ROM project. Early on, it was intended that the module housing be made of clear plastic (probably acrylic or polycarbonate) rather than the usual dark brown ABS. It would have been called the "Clear Advantage".

While clear plastic case parts were used for some prototype calculators, they generally are not as rugged as ABS. It was decided that the "Clear Advantage" didn't meet HP standards, so the idea was shelved, and it ended up using the same ABS plastic housing as almost all of the HP-41 modules.

Trivia question of the day: which module for the HP-41 does NOT use the same ABS plastic for its housing, and why?

Maybe the IR Printer module? Because part of it needs to be IR-transparent?


The following HP modules do not have the standard ABS plastic housing:

HP-IL module: module too large
HP-IR module: red eye did not fit in the housing
HEPAX: made by VM Elecronics
CMT Eproms: small slit on both sides
ZEPROMs: whole to erase by UV light
MBK EPROM module holder: prototype

Did I miss a module?

HP-IL module uses the same ABS as all other normal 41 modules.

Yes, that's the one. The entire module housing is molded from IR-transmissive plastic.

Here's a pic of the rom. You can see it's made from the basic ABS material as most others are. There are some numbers stamped in the shell, I believe the number is 8525, not sure if it's a serial number for the internal chip or not. I'll confirm the number tomorrow as I left it in my calc at work.


Only way you will find out the value is to set a high reserve on a certain auction website and see where bidding goes.... Make sure and offer an international shipping option (probably insured) so that the world can give input into bidding.

Use this picture and the description you have given to this point...

Excuse this, but it is necessary per new rules. Disclaimer: I am not criticizing or commenting on an ebay auction, I am only suggesting a potential auction to happen.