Multi-drive, multi-magazine mass storage and retrieval unit for tape cartridges

A multi-drive, multi-magazine mass storage and retrieval unit for tape cartridges which automatically retrieves a selected one of a plurality of tape cartridges from one of a plurality of tape cartridge magazines for transfer to a selected one of a plurality of tape drives. The unit further retrieves a selected one of a plurality of tape cartridges from one of the plurality of tape drives for storage in one of the plurality of tape cartridge magazines. A tape cartridge elevator retrieves and transports the tape cartridges between the plurality of tape cartridge magazines and the plurality of tape drives. An interunit cartridge transport unit enables multiple tape storage and retrieval units to be coupled together and cartridges to be passed automatically between the coupled units.