The IBM 2321 Data Cell Drive was an elaborate mass storage device used with the IBM System/360. The drive held ten cells like the one here, arranged to form an upright cylinder. Each data cell in turn held 20 subcells, and each subcell contained ten magnetic sheets. A sheet stored data in 100 tracks. To access data, the cylinder was spun to the appropriate subcell, the subcell was extracted and the magnetic sheet pulled for reading or writing. The entire drive could hold 400 megabytes and as many as eight drives could be hooked up to the System/360. In addition, data cells and individual subcells could be quickly swapped by hand. By the end of its lifetime in 1975, however, it had been overtaken by magnetic disks.