The card you guys are thinking of is the MCR04 MegaRAM card. It is a single card with two 2-position switches which allows you to select between 4 banks on the card. Each bank is the equivalent of a single MCR03 256k(32K) RAM card. They have the Korg name on them, but I believe they were manufactured by Mitsubishi for Korg. It should work with the M1 because the keyboard only views the MegaRAM card as a single 256k(32K) card - flipping the two switches allows you to access other banks on the card and the board would perceive it as a new card being inserted in the card slot. I have 3 MegaRAM cards, but they are not for sale. The are extremely hard to come by, but you can still find them. I do have brand new 256k cards (MCR03 style) that are available for $35 each. If you are interested please let me know. Regards, Thomas