Abstract: A CD-ROM tower holds 100 CD-ROM disks or like media in five removable magazines. The magazines are identifiable by a robotics control system in the tower. The tower further includes four drives which receive the disks and transfer data from the disks to a SCSI bus. A transport mechanism controlled by the robotics control system raises and lowers an elevator with respect to the magazines and the drives. A tray picker mechanism on the elevator pulls a tray out of a magazine, and a disk lifter mechanism on the elevator lifts a disk from the tray. After the tray is returned to the magazine, the elevator is moved a drive and the disk is lowered onto the drive drawer. In similar manner, a disk is removed from a drive drawer and returned to a magazine tray. The tower is configured to use commercially available CD-ROM drives or other media drives so that the drives are available at commodity prices and are easily replaceable and upgradeable.

Abstract: A method accesses and updates information from a library of optical discs and includes a step of cataloging optical discs. The cataloging step includes the generation of a unique value for each of the cataloged discs. The unique value is produced by iteratively reading data from each disc and iteratively combining the data. The cataloging step includes the generation of catalog data streams. The catalog data streams include fixed length data representing file and directory attributes and variable length data representing file names and directory names. The method includes the further step of producing limited depth catalogs representing file and directory information on the optical discs. The limited depth catalogs have a fixed number of subdirectory levels and file types. The fixed number is selected by a user, and the file types are selected by a user. The method includes the further step of caching optical disc data to a hard disc.