<hardware, storage> (MO) A plastic or glass disk coated with a compound
(often TbFeCo) with special optical, magnetic and thermal properties. The disk
is read by bouncing a low-intensity laser off the disk. Originally the laser was
infrared, but frequencies up to blue may be possible giving higher storage
density. The polarisation of the reflected light depends on the polarity of the
stored magnetic field.
To write, a higher intensity laser heats the coating up to its Curie point,
allowing its magnetisation to be altered in a way that is retained when it has
Although optical, they appear as hard drives to the operating system and do not
require a special filesystem (they can be formatted as FAT, HPFS, NTFS, etc.).
The initial 5.25" MO drives, introduced at the end of the 1980s, were the size
of a full-height 5.25" hard drive (like in IBM PC XT) and the disks looked like
a CD-ROM enclosed in an old-style cartridge
In 2006, a 3.5" drive has the size of 1.44 megabyte diskette drive with disks
about the size of a regular 1.44MB floppy disc but twice the thickness.
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magneto-optical disk » magneto-optical drive »
magnetostrictive delay line » MAGNUM
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