A disc storage device rack includes: an accommodation space surrounded by left and right side plates and upper and lower partition plates and configured to accommodate a disc storage device; a guide portion provided on the side plates and configured to fit to a guided unit provided in the disc storage device to guide a sliding operation of the disc storage device; and a shutter provided on each end surface of the side plates so as to be slidable in an up-and-down direction and configured to open an opening of the guide portion when the disc storage device is pulled out from the accommodation space or when the disc storage device is pushed into the accommodation space.

The disc device comprises disc selector spindle that hold discs in a stacked state, separate lowermost disc from other discs, and supply separated lowermost disc to drive unit. The disc selector spindle includes first, second, and third support claws that move to storage position at which each support claw is stored inside center hole of disc and protrusion position at which each support claw protrudes in a region located in the vicinity of inner diameter of disc in plan view. First support claw moves to storage position and protrusion position independently of the movements of second support claw and third support claw. Second support claw is disposed so as to be shifted from third support claw in a stacking direction of disc by a thickness of one disc, and to move from storage position to protrusion position at a timing different from a timing of third support claw.

A tape-type magnetic recording medium, includes a substrate; and a magnetic layer provided on the substrate. The magnetic recording medium is configured such that (1) (w.sub.maxw.sub.min)/w.sub.min400 [ppm] where w.sub.max and w.sub.min are respectively maximum and minimum of average values of width of the magnetic recording medium measured under four environments whose temperature and relative humidity are (10 C., 10%), (10 C., 80%), (29 C., 80%), and (45 C., 10%), respectively, and the magnetic layer has a squareness ratio of 65% or more in the vertical direction, and (2) 4.4T.sub.B/(T.sub.AT.sub.B) where T.sub.A is an average thickness of the magnetic recording medium and T.sub.B is an average thickness of the substrate.

A magnetic recording medium is provided and including an average thickness t.sub.T satisfies t.sub.T5.5 [m], and a dimensional change amount w in a width direction of the magnetic recording medium with respect to a tension change in a longitudinal direction of the magnetic recording medium satisfies 700 [ppm/N]w.

A cartridge includes a tape-shaped magnetic recording medium and a cartridge memory. The cartridge memory includes a communication unit that communicates with a recording/reproducing device in a state where the cartridge is loaded on the recording/reproducing device; a storage unit; and a control unit that stores information received from the recording/reproducing device through the communication unit in the storage unit, reads the information from the storage unit according to a request from the recording/reproducing device, and transmits the information to the recording/reproducing device through the communication unit. The information includes manufacturing information of the cartridge and adjustment information for adjusting a tension applied to the magnetic recording medium in a longitudinal direction thereof, and the tape-shaped magnetic recording medium has a plurality of servo bands.

A magnetic recording medium is provided and including an average thickness t.sub.T satisfies t.sub.T5.5 [m], and a dimensional change amount w in a width direction of the magnetic recording medium with respect to a tension change in a longitudinal direction of the magnetic recording medium satisfies 700 [ppm/N]w.

A disc storage device rack includes: an accommodation space surrounded by left and right side plates and upper and lower partition plates and configured to accommodate a disc storage device; a guide portion provided on the side plates and configured to fit to a guided unit provided in the disc storage device to guide a sliding operation of the disc storage device; and a shutter provided on each end surface of the side plates so as to be slidable in an up-and-down direction and configured to open an opening of the guide portion when the disc storage device is pulled out from the accommodation space or when the disc storage device is pushed into the accommodation space.

A cartridge is provided and includes tape-shaped magnetic recording medium; and cartridge memory; wherein cartridge memory includes communication unit that communicates with recording/reproducing device in state where cartridge is loaded on recording/reproducing device; storage unit; and control unit that stores, reads, and transmits information, wherein information includes manufacturing information of cartridge and adjustment information for adjusting a tension applied to the tape-shaped magnetic recording medium in a longitudinal direction of tape-shaped magnetic recording medium thereof, tape-shaped magnetic recording medium has a plurality of servo bands, and wherein a temperature expansion coefficient ? of the tape-shaped magnetic recording medium satisfies 6 ppm/? C.???8 ppm/? C.