disk cartridge

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disk cartridge An exchangeable disk store, now obsolete, that took the form of an assembly containing a single rigid magnetic disk permanently housed within a protective plastic cover. It was introduced by IBM in 1964. The cartridge, according to its type, could be loaded vertically onto its drive (top-loading), or horizontally from the front (front-loading). Either way the cartridge hub, to which the disk was clamped, centered onto the drive spindle and was magnetically clamped. The cover contained apertures to allow fixing of the cartridge to the drive, and a door that the drive opened to allow insertion of the magnetic heads. Once loaded, the disk could rotate clear of the covers. Disk cartridges had storage capacities up to 50 megabytes, depending on track density, bit density, and disk size.

Similar cartridges are used for optical disks, with capacities from a few hundred megabytes to several gigabytes. In some cases the disk is extracted mechanically from the cartridge for use, rather than rotated within it.