The First Removable Disks
IBM introduced the first hard drive with removable disks--the IBM 1311 (shown here in the upper right image)--in 1963. It used interchangeable disk packs, each composed of six 14-inch-diameter disks. Each disk pack stored about 2MB of data. Many 1970s-era hard drives, such as the DEC RK05 (a similar model appears in the image to the far left), accommodated disk packs, which minicomputer companies often used for software distribution.
Photos: Lawrence Livermore National Laboratory Technical Information Department/IBM