HP41.org

Hello together,

A few days ago I bought a HP41CV from a local garage sale in good conditions, only the battery contacts were corroded. After opening the housing for better cleaning and repairing the contacts, I saw an unknown modification and now I'm not sure, if this is an original option. Also I don't know which function does this PCB have. Maybe this is an extra memory or other functionality module?

Google doesn't help me about PCBs numbering "5081-5558" and also I cannot find any photos or articles of a similar modification. Does someone know such a modification or the function of this two extra PCBs? I will be grateful and happy for every hint.

Thanks and regards,
euleken

Photo(s) of the other side of the board may help as one may be able to see the p/n on the chips, which could help to ID them.

Most likely these are 2 ROM modules, soldered inside the case. Services to move these modules inside were offered, back in the day, by EduCALC, SOS and other specialty firms, to leave the 4 ports available for more modules. Another possibility is these are 2 X-MEMORY modules, which were also installed inside for the same reason. Since the boards have the same p/n they are clearly of the same type (as opposed to one being the X-Func/Mem and the other just X-MEM).

hth

Hi rprosperi,

below I put a photo of the front side of the board/chips, but there's no numbering or any other signs.
I'm not very firm with handling of the HP41 yet and I don't know how I could read-out or test modules and optional functions. It would be nice to get some help here to identify this build-in hardware and for its checking.

Regards,
euleken

Indeed, no information at all on that side, but thanks for trying.

To answer your original question, this definitely was NOT an original HP option, this was definitely a 3rd party modification to embed ROM or X-MEM modules inside the case.

Why not reassemble the case after cleaning the contacts appropriately and then it will be easy to check what they are.

If ROM, then CAT-2 will reveal which ones.

If X-MEM, check initially using XEQ "EMDIR" which would show a catalog of EXT-Mem and return the amount of available Ext-Mem. If that result is "NONEXISTENT" (meaning Ext-Func/Mem module is not present), insert an EXT-Func/Mem module and try again. When empty, 1 x Ext-Func/Mem & 2 x X-Mem modules should have 603 registers available.

Thanks for this hint.
After installing a XFunction module the command XEQ EMDIR shows 600 registers of extended memory, so the built-in modules are two XMemory HP 82181. It seems curious for me, why there are two XMems installed and not one XFunction and one XMemory module...
Ok, I will not bitch. I bought this calculator very cheap and the seller (and also I) didn't know about the built-in extra memory. It was a lucky punch.

Great, thanks for confirming these hints were helpful, and congratulations on acquiring a quite rare 41 configuration.

Interesting.
Instead of creating "Double X-Memory Module" (taking 2 X-Memories and soldering it into 1 housing X-Memory), it is now possible to "Upgrade HP41CV with 2 X-Memories" (no port busy by it).
Perhaps a precise HowTo (picturing etc.) of that rare hardware setup would allow others to copy it?

Hey Floppy,

You need to get in touch with Jake Schwartz to get the PPC Archive usb drive. V8n1 is the issue that covered an internal module installation. It is a great investment with a wealth of information.

http://www.pahhc.org/ppccdrom.htm

Check it out.

-Bill

Thanks Bill for the answering.
My understanding after exchange offline with others:
HP41CV: bringing X-memory and X-functions parts inside an HP41CV dont free all ports.
However, your CV is very interesting.
I will not change for now my CV with your design but still focus on the use on my CX with Nov64d and double X-Memory in 1 module.