[41CL] Memory Reference posted


I just posted a stand-alone memory reference for the 41CL here: 41CL Memory Reference.


Fantastic document Monte, thanks a million - it sure conveys the remarkable dimension of the RAM-Flash within the CL, and the sheer number of modules that populate it.


Thanks Monte, I continue to be amazed by the power of the 41CL.
Thanks also to Angel for all your dedication to the HP41.
Kind Regards


Hi Monte, this is great very useful. Printed out in a small notebook, makes it much easier to track memory allocations and locate ROMS. Appreciated.


Needed & wanted.



Thanks Monte,

Very useful indeed !

Using the 41CL regularly... I simply forgot I could upgrade my beta treasure...

I'm about to move to 4C but even after browsing the forum, I still have 2 questions :

- Is there any recommendation to migrate to YFNP instead of YFNZ and the reasons why ? (I already have the IMDB in flash)

- If I flash the Modified Time Module image on my beta board, will it overtake automatically the one already present or do I need to PLUGx it.

Many thanks again Monte !


Edited: 28 Apr 2013, 10:54 a.m.


Very impressive! Wonder if we'll see a 41CL emulator for iOS?



Hi Etienne,

Because you have a beta board, the logic in the fpga does not support the OS remapping that is required if you want to update the OS sector of the Flash. If you want to return the board to me and cover my return postage I'll be happy to update the programmable logic to the latest version (or did I already do that for you? I forget...), and at the same time update the Flash contents. Be aware that because the Flash on the beta and first batch of boards is half the size of later boards, not all images can be loaded. Just let me know if you want to do this.

If I already updated the programmable logic for you, let me know and I can send you the instructions for updating an image in the protected sector. As far as YFNZ/YFNP, I personally use YFNP on all of my machines. I use the IMDB functions much more than I do the memory buffer functions.

As far as your original question, once the new time module image is loaded, in place of the original, the new image will always be the one that is used. Because the location of the time image is "known" by the hardware, you can't just substitute a different image in a different location.



Hi Monte,

Many thanks for your detailed answer and also for the kind proposal.

Yes indeed, you already updated my beta at YFNS -2B a while ago but I have no way to ascertain the programmable logic was updated.

However, reading 41CL B20955 status (04/24/2012) my understanding is that this new programmable logic was implemented starting with -3B (maybe I'm wrong).

I fully understand the impact of the beta flash size on the available Roms but do appreciate your proposal and will send back the board for programmable logic and flash update.

I'm highly interested in having the updated Time Module image and the YFNP burned in.

Thank you very much again.

Even though I don't post much, I use my CL on a regular basis (with POWERCL).



Hi Etienne,

Going back through the shipping records, the programmable logic on your board was updated with the first version of the MAPEN functionality, which had a bug. So sending it back is the right way to go. I'll load the latest logic (with MAPEN fixed, banks for pages 6 & 7, and two-key rollover fixed) as well as all of the latest images.

Best regards, Monte


Hi Monte,

I will go this route then, thanks much !



Hi Etienne,

in addition to the reasons already mentioned by Monte, remember that the POWERCL includes those functions from YFNS not present in YFNP, so you won't be missing anything going this way.

The POWERCL function launchers assume the IMDB functions are available, i.e. it's based on the YFNP.

Hope this helps,


Hi Ángel,

Thank you ! It does help a lot.

I use the June 2012 POWERCL revision (after months with CLUTILS) and the great work you did with the manual (actually all your manuals) + Monte's Memory reference prompted me to upgrade !


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