magneto-optical disk
(foldoc) | magneto-optical disk
magneto-optical drive
M O drive
(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 cooled.
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.
{Storage FAQ
(http://cis.ohio-state.edu/hypertext/faq/usenet/arch-storage/part1/faq.html)}.
(2006-07-25)
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