An early removable disk drive from IBM that put the heads and platters (disks) in a sealed unit for greater speed. Before the Winchester architecture, removable disks were like removable disks today, in which the read/write heads remain in the drive and make contact with the platter after the cartridge is inserted.

Introduced in 1973 as the model 3340, the drive had one permanent and one removable spindle, each holding 30MB. The "30-30" storage capacities led to the Winchester nickname after the Winchester 30-30 rifle. The term later referred to all fixed hard disks because the heads and platters are always encased in the same, sealed unit. See also Winchester.