Abstract: A plurality of modules are removeably mounted in a rack. At least one of the modules is a drive module including a tape drive and at least one of the modules is a storage module including a carrousel for removeably receiving a plurality of magnetic tape cartridges. The storage module includes mechanisms for rotating the carrousel to present a selected cartridge to a withdrawal and replacement position. The drive and storage modules have track segments which are aligned in end-to-relation. A robot carries the selected cartridge between the carrousel and the tape drive. The robot includes a carriage mounted for traveling along the track segments and a gripper for gripping and releasing the selected cartridge. The system further comprises a control and sequencing circuit for rotating the carrousel, moving the carriage and operating the gripper.