A floppy disk cartridge adapter having a removable coin shaped memory disk. The 31/2 inch size cartridge adapter can fit into conventional personal computer disk drives. The small coin shaped magnetic disk has a diameter of approximately 1 inch, and can be easily snapped into and removed from the cartridge adapter. The coin disk fits on a spindle that is side by side to the floating drive plate used in regular 31/2 inch floppy diskettes. The spindle can be attached by various drive systems to rotate simultaneously with the rotating drive plate. One version is belt driven, another has the coin disk snap onto a spindle supported wheel whose sides frictionally rub against the drive plate wheel, and a third version has the coin disk snap onto the spindle supported gear wheel whose sides contain teeth which mateably engage like side teeth on the drive plate wheel. The coin disk can alternatively be inserted into a separate casing having a spring loaded shutter so that the conventional disk drive being used can access the magnetic sides of the coin disk by sliding the shutter. When removed from the cartridge adapter, the disk can be inserted into a small clip retainer which has a paper clip edge allowing the coin shaped disk to be portably mounted on papers, cardboard, clipboards and the like.
