magnetic disk

3 definitions found

magnetic disk - 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]

magnetic disk - WordNet (r) 2.1 (2005) :

  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]

magnetic disk - Free On-line Dictionary of Computing (26 May 2007) :

  magnetic disk
  
     <storage> A flat rotating disc covered on one or both sides
     with some magnetisable material.  The two main types are the
     hard disk and the floppy disk.
  
     Small areas or "zones" on a magnetic disk are magnetised.  The
     magnetisation is aligned in one of two opposing orientations
     with respect to the recording head.  The head writes data
     by altering the alignment and reads data by detecting current
     pulses induced in a coil as zones with different magnetic
     alignment pass underneath it.
  
     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
     though, for increased performance (from reduced rotational latency
     ), it is possible, though expensive, to position
     multiple heads at equally spaced angles around the discs.
  
     Therefore there are two states that can be detected for each
     zone - a change in alignment, or no change.
  
     Ideally a data bit of one or zero can be recorded in each zone
     of magnetisation, however, if a zero represents an absence of
     magnetic change, the detection of several consecutive zeros
     would imply accurately measuring the length of time of the
     absence, i.e., measuring the time between two magnetic
     changes.  However, the variability of motor speed limits the
     number of consecutive zeros which can be read reliably.
  
     The best recording methods accurately follow the
     characteristics of the magnetic and rotational aspects in
     recording the disk, to be as dense as possible in recording
     bits.
  
     Compare magnetic drum, compact disc, optical disk,
     magneto-optical disk.
  
     (2003-03-10)