[HP-48GX] Expansion slot info needed

[Kikicat123]

Hello all, First time posting here so I hope I got the correct place in the forum.

I want to make my own 128K RAM card because the ones I can find second-hand are incredibly expensive, and as far as I can tell there isn't anyone making new ones. I have been able to find a pinout for the expansion cards, however I am missing a few crucial details:

• I need the physical dimensions of the cards themselves - Width, Height, and also Thickness.
• Additionally, I also do not know what the voltage is going to the cards, only that it is VDD.
• It would also help if someone could measure the power draw of one of the cards while in use - This will let me see how much power I can pull from VDD.
  

Also, is it worth trying MRAM (Magnetoresistive RAM) as a non-volatile replacement for a SRAM chip? If it worked, it wouldn't need a battery, at least in theory.

Thanks,
Robert