Abstract: A magnetic tape library apparatus having a bar code reader. The apparatus comprises a cell unit for housing magnetic tape cartridges, a drive unit for performing write and read operations on each magnetic tape cartridge, a cartridge access station for loading and unloading magnetic tape cartridges, an accessor for transferring each magnetic tape cartridge along a predetermined path, and a bar code reader station located along the path of the accessor. The bar code reader station includes a rotatable table on which to place a magnetic tape cartridge, and the bar code reader capable of reading a bar code from the magnetic tape cartridge placed on that table.

Abstract: A library apparatus having components permitting accurate and straightforward assembly. The library apparatus includes respective cell, drive, accessor and passage units, each having box shaped housings including a connection mechanism. A coupling couples the housings of the passage units with the other units. Other features of the library apparatus include a reference mark on the accessor unit which permits a transport mechanism in the passage unit to correct positional errors of the transport mechanism to other components.