Floppy disks, also called diskettes, work along the same principles as hard disks, so we will only discuss hard disks in this chapter. The terminology refers to the flexibility of the magnetic medium used. Floppy disks are just pieces of Mylar plastic coated with an iron-based "paint" that can be magnetized, while hard disks use the surface of a non-flexible platter as the base for their "paint." Floppies started out huge, 8 inches in diameter, and were originally designed only for IBM field diagnostics. Minicomputers of the early 1980s still used 8" floppies. Then 5.25" diameter floppies were made and used in most microcomputers until the late 1980s when they were supplanted by the now current 3.5" diameter floppies. The current 3.5" diskettes really don't seem floppy any more because the round Mylar surface is hidden in a hard plastic case that only the computer can open, whereas the older diskettes were kept in a sleeve and manually taken out of the sleeve by a human before being inserted into a disk drive.