Special Module for HP-41CX


I want to understand the difference between the special modules made for HP-41 like CCD, ZENROM etc.

Somebody can explain me and tell me how to find these?

Thanks and happy new year


Hello Fabio,

Guess we could say that the HP41C "Special Modules" are modules not programmed by HP. There are too many for me to list here however, Matthias Wehrli has a .pdf which lists almost all of them along with some data for each module:


As far as "find these"; eBay or the Classified Ads here (place a "wanted" ad) are the best bets yet some modules are VERY rare (nearly impossible to find).

The modules that you mention (CCD, ZENROM) are micro-coded roms, whereas many special roms are user-coded roms. The other possibility is using an MLDL device to load module "image". Two such devices are currently being produced: the Clonix/NoVRAM and the MLDL2000. Google is your friend.

Best Regards

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