Editing MiniDisc (section)

=== Physical characteristics ===
[[File:Memorex-minidisc.jpg|thumb|[[Memorex]] Mini-Disc]]

The disc is fixed in a cartridge (68×72×5&nbsp;mm) with a sliding door, similar to the casing of a 3.5" [[floppy disk]]. This shutter is opened automatically when inserted into a drive. MiniDiscs can either be blank or prerecorded. Recordable MiniDiscs use a magneto-optical system to write data: a laser below the disc heats a spot to its [[Curie point]], making the material in the disc susceptible to a magnetic field. A magnetic head above the disc then alters the polarity of the heated area, recording the digital data onto the disk. Playback is accomplished with the laser alone: taking advantage of the [[magneto-optic Kerr effect]], the player senses the polarization of the reflected light as a 1 or a 0. Recordable MDs can be rerecorded repeatedly, with Sony claiming up to one million times. By May 2005, there were 60-minute, 74-minute and 80-minute discs available. 60-minute blanks, which were widely available in the early years of the format's introduction, were phased out.

MiniDiscs use a mastering process and optical playback system that is very similar to CDs. The recorded signal of the premastered pits and of the recordable MD are also very similar. [[Eight-to-Fourteen Modulation]] (EFM) and a modification of CD's [[Cross-Interleaved Reed-Solomon Coding|CIRC]] code, called Advanced Cross Interleaved Reed-Solomon Code (ACIRC) are employed.