A
magneto-optical drive is a kind of
optical disc drive capable of writing and rewriting data upon a
magneto-optical disc. Both 130 mm (5.25 in) and 90 mm (3.5 in) form factors exist. The technology was introduced commercially in 1985. Although optical, they appear as
hard disk drives to the
operating system and can be formatted with any
file system. Magneto-optical drives are common in some countries, such as Japan because of the success of the
Sony MiniDisc, but have fallen into disuse in other countries.