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I am trying to make a double Xmem module according to the well known specs but since I am doing this for the first time there is one thing that I am not quite clear about. Should the B3 line be totally disconnected from the connector pin that goes into the calculator port? Document by Christoph Klug that I am using as a guideline suggests that. At least that is how I am interpreting it.

1234 to delete.


One module must be in port 1 or 3, the other in port 2 or 4 to be able to operate correctly. It is probably best to hardwire one module to port 1, and the other to port 2, regardless of which port it is really plugged.
This means that you do not connect B3 and B4 of the module connector at all, but rather connect the pads on the module PCB itself to GND and Vcc:

Module 1: B3 + B4 to Ground (Port 1)
Module 2: B3 to Vcc, B4 to GND (Port 2)


Hi Miki,

Just to point out a different approach, (which I used in my own double X-Mem)

As for Meindert's config, you always get your X-Mem modules into PORTS [1 + 2] regardless of the port you physically connect your module.

You may want to keep some "fexibility", being able to choose between ports [1 + 2] or [3 + 4] depending on wich port you physically plug your double module in. Just connect B4 line to the connector strap, and put one module's B3 to GND while keeping the other's B3 tied to V+.

With these config you'll find your memory at ports 1 & 2 when plugged at ports 1 *or* 2. (obviously same scheme for ports 3 & 4).

Wichever approach you choose, please let us participate of your success!!! ;-))

Best wishes.


Dear XX-Memory enthusiasts,

the more universal configuration of Diego I also described in my documentation about creating Double X-Memories.

From a XX-Memory resuls a really powerfull HP41 port configuration. For example :

Port 1 = Zeprom or Clonix
Port 2 = XX-Memory
Port 3 = IL-Module
Port 4 = free for user applications or Card Reader

Inside Zeprom or Clonix I prefer the rom-image-files of CCD + EXT-I/O + EXT-IL module....

Regards from Germany - Christoph Klug