magneto-optical disk

magneto-optical disk
magneto-optical drive
M O drive

   <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 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)