MiniDisc (MD) is an erasable magneto-optical disc-based data storage format offering a capacity of 60, 74, and later, 80 minutes of digitized audio.
MiniDisc by TDK, with AA battery for scale
The Sony MZ1, the first MiniDisc player, released in 1992.
Pioneer MiniDisc car receiver
Sony Hi-MD Recorder MZ-RH1, released 2006
A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. 130 mm (5.25 in) and 90 mm (3.5 in) discs were the most common sizes. In 1983, just a year after the introduction of the compact disc, Kees Schouhamer Immink and Joseph Braat presented the first experiments with erasable magneto-optical compact discs during the 73rd AES
Convention in Eindhoven. The technology was introduced commercially in 1985. Although optical, they normally appear as hard disk drives to an operating system and can be formatted with any file system. Magneto-optical drives were common in some countries, such as Japan, but have fallen into disuse.
A Magneto-optical disc surface has sector partition rectangles.
Visible sectors partition lines on a 130 mm 652 MB magneto-optical disk. (1024 user byte, 17 sectors per track).
A 130 mm 2.6 GB magneto-optical disc
A 230 MB Fujitsu 90 mm magneto-optical disc.