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3 definitions found
 for magnetic disk
From The Collaborative International Dictionary of English v.0.48 :

  magnetic disc \magnetic disc\, magnetic disk \magnetic disk\n.
     A ditical memory device consisting of a flat disk covered
     with a magnetic coating on which information is stored; a
     hard disk, floppy disk, and diskette are typically
     magnetic disks.
  
     Syn: disk, disc.
          [WordNet 1.5]

From WordNet (r) 3.0 (2006) :

  magnetic disk
      n 1: (computer science) a memory device consisting of a flat
           disk covered with a magnetic coating on which information
           is stored [syn: magnetic disk, magnetic disc, disk,
           disc]

From The Free On-line Dictionary of Computing (18 March 2015) :

  magnetic disk
  
      A flat rotating disc covered on one or both sides
     with magnetisable material.  The two main types are the hard
     disk and the floppy disk.
  
     Data is stored on either or both surfaces of discs in
     concentric rings called "{tracks".  Each track is divided
     into a whole number of "{sectors".  Where multiple (rigid)
     discs are mounted on the same axle the set of tracks at the
     same radius on all their surfaces is known as a "{cylinder".
  
     Data is read and written by a disk drive which rotates the
     discs and positions the read/write heads over the desired
     track(s).  The latter radial movement is known as "{seeking".
     There is usually one head for each surface that stores data.
     To reduce rotational latency it is possible, though
     expensive, to have multiple heads at different angles.
  
     The head writes binary data by magnetising small areas or
     "zones" of the disk in one of two opposing orientations.  It
     reads data by detecting current pulses induced in a coil as
     zones with different magnetic alignment pass underneath it.
  
     In theory, bits could be read back as a time sequence of pulse
     (one) or no pulse (zero).  However, a run of zeros would give
     a prolonged absence of signal, making it hard to accurately
     divide the signal into individual bits due to the variability
     of motor speed.  Run Length Limited is one common solution
     to this clock recovery problem.
  
     High speed disks have an access time of 28 milliseconds or
     less, and low-speed disks, 65 milliseconds or more.  The
     higher speed disks also transfer their data faster than the
     slower speed units.
  
     The disks are usually aluminium with a magnetic coating.  The
     heads "float" just above the disk's surface on a current of
     air, sometimes at lower than atmospheric pressure in an
     air-tight enclosure.  The head has an aerodynamic shape so the
     current pushes it away from the disk.  A small spring pushes
     the head towards the disk at the same time keeping the head at
     a constant distance from the disk (about two microns).
  
     Disk drives are commonly characterised by the kind of
     interface used to connect to the computer, e.g. ATA, IDE,
     SCSI.
  
     See also winchester.  Compare magnetic drum, compact
     disc, optical disk, magneto-optical disk.
  
     http://pc-disk.de/)">Suchanka's PC-DISK library (http://pc-disk.de/).
  
     (2007-06-14)
  

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