Abstract: A data storage device comprises a cartridge receiving stop having a middle surface and angled outer edges for inhibiting the insertion of incompatible disk cartridges into the data storage device. A disk cartridge adapted for use in the data storage device has opposite front corners. The opposite front corners of the disk cartridge have a non-square shape adapted to avoid interference with the angled outer edges of the cartridge receiving stop. The data storage device may further comprise means for enabling a function of the data storage device upon insertion of a disk cartridge having non-square front corners into the disk drive. The disk cartridge may further comprise a projection positioned on the front peripheral edge of the disk cartridge and adapted to engage an operating member of the enabling means on the middle surface of the cartridge receiving stop.

Abstract: A magnetic recording disk cartridge comprises a flexible recording disk having a cylindrical hub secured to the central portion thereof, and a casing in which the recording disk is accommodated. The cartridge is provided with a locking member comprising a pair of resilient arms which are fixed to the casing and are urged toward each other to grip therebetween the hub to fix the recording disk with respect to the casing so that the surfaces of the recording disk are not brought into contact with the inner surface of the casing, and a releasing member movable between an inoperative position in which it is operatively removed from the resilient arms and an operative position in which it urges the resilient arms away from the hub to release the recording disk from the locking member. The releasing member is arranged to be automatically moved to the operative position when the cartridge is loaded in a system using it, e.g., an electronic camera.