A data storage system comprises a magnetic disk, an optical disk, optical disk drive units, and optical disk transport devices for transporting the optical disk to the optical disk drive units as required. The data storage system further comprises a host system for receiving and transmitting a command...http://www.google.de/patents/US5313617?utm_source=gb-gplus-sharePatent US5313617 - Multi-disc optical data storage system for use with a host computer for emulating a magnetic disc device
