HP-41CX Extended Memory

[Jeff Davis]

I was wondering since the extended memory modules do get rather expensive and are rarely found any more, is there any way to take an old Math pac, for instance as I have one that does not work, and remove the chip and then put together an Double Extended memory module. What chip was originally used? Is there a schematic for the Module anywhere?

[Eric Smith]

The extended memory module uses four custom HP chips directly bonded to the PCB and encapsulated in epoxy. There is no commercially available memory chip that will work in an HP-41.