(MFM, Modified
FM, or sometimes "Multiple
Frequency Modulation") A modification to the original
frequency modulation scheme for encoding data on magnetic disks. MFM allows more than 1 symbol per flux transition (up
to 3), giving greater density of data. It is used with a data
rate of between 250-500 kbit/s on industry standard 3.5" and
5.25" low and high density diskettes, and up to 5 Mbit/s on
ST-506 hard disks. Except for 1.44 MB floppy disks, this
encoding is obsolete.
Other data encoding schemes include
GCR,
FM,
RLL. See
also:
PRML.