Can some one tell me the use of the PPC ROM; what is it for?
I'm familiar with Aviation, Navagation, Surveying Etc...
Have not seen any for sale...is there an emulator for it? How much does it cost?

Thanks !


Please take a look here:


and on TOS, which can be reached from here:





The PPC-ROM was the fruit of the PPC club which was lead by Richard Nelson. The ROM came to be in the early 80s and as a result of the contribution of many ace club members who had a beautiful zeal about using the HP-41. The highlight of the PPC-ROM was the use of synthetic-programming commands to create routines to make things either easier or even at all possible.

The HP musuem CDs contain a copy of the PPC-ROM. If you have a copy of the CDs (or DVD) please look in it. If not, I encourage you to buy the museum CDs or DVD.



I was just thinking....could the PPC ROM project be considered one of the earliest open-source projects? When the ROM was released, the first IBM PCs were just coming off the assembly line.

Jake Schwartz


Hi Jake,

Very good question. I think Richard can answer that. The HP-41CX emulator on TOS has a MOD file for the PPC-ROM. From the little testing (a few months ago) I did with that emulator I got the impression that it was a partial implementation.



could the PPC ROM project be considered one of the earliest open-source projects?

Not really. Almost all computer software written in the 1950s and early 1960s was open-source. That was not just the case for user-developed software, but also vendor-developed. For instance, software published by IBM was open-source until 1969.

The PPC ROM is perhaps an example of a relatively early case of a geographically distributed collaborative open source project. Before the widespread availability of modems, most collaborative software development tended to occur between authors in close physical proximity.


WoW..This is Beautiful... Given that it was developed around 1980, are there different module versions? (like on the surveying and aviation; HP developed a few versions). Why wasn't the PPC ROM more accesible to regular users. Where can I find one today and how much should I pay. Will this module work on all 41C or do I need a high end 41CX?. How much memory is required...I apologize for the load of questions but..The more I get into it, the more it blows my mind...THANK YOU NAMIR, JAKE, RAYMOND AND ERIC.... (I WILL BUY THE LATEST DVD)...
I appreciate you input.


Why wasn't the PPC ROM more accesible to regular users

It was targetted to sophisticated users, but PPC would sell it to anyone. IIRC, for a while, HP included information about PPC (but not specifically the ROM) in the packaging with new HP-41s.

Will this module work on all 41C or do I need a high end 41CX?

Works fine on any 41. On a 41CX (or a 41C or 41CV with Time Module), some functions such as those relating to key assignments may not work correctly. At the time the PPC ROM was written, the Time Module was not yet available, and it wasn't generally known how the 41's I/O buffer scheme worked. The I/O buffers, one of which is used for timer alarms, live below the key assignments in memory.

Still, most of the PPC ROM routines work fine even on a 41CX or with a Time Module.


Dear North Docota,

a virtual PPC Rom is also available for the EMU41 software emulator.

Today the PPC ROM is a nice part for collectors - and the belonging user manual (in the size of an heavey telephone book) is one of the greatest HP41 publications I know.

But for practical work today with the HP41, the later CCD Module gives you better performance and faster commands than the PPC ROM. The CCD Module includes synthetic programming and array functions and a lot of helpfully software tools.

PPC Rom is programmed by user language plus some synthetic. CCD is a complete mcode solution.

Raymond Del Tondo creates a extract of the CCD Module by removing the array functions (which also exist in the Advantage Module). Raymonds CCD Module version is called CCD OS/X and needs one 4KByte block. Also Angel Martin creates a own 8KByte version of the CCD Module.

By loading NOVRAM or CLONIX with PPC rom image files you are able to use the PPC or the CCD with your real handheld.

Because PPC and CCD are nice parts for collectors, their prices are really high - therefore using an emulator like V41 or EMU41 for learning something about this great modules would be a good first step solution.

In a later step using CLONIX or NVRAM would be possible with a lower price (and better HP41 plug in port configuration) than using the original modules for high prices....

Best wishes from Germany - Christoph Klug


At the time the PPC ROM was written, the Time Module was not yet available, and it wasn't generally known how the 41's I/O buffer scheme worked.

hp, of course, knew this information, and chose not to share it with PPC -- even though they were aware that some of the PPC ROM functions were monkeying around in the buffer area. I recall Richard Nelson mentioning something to the extent of "hp really screwed us big time on that one!"

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