floppy disk drive

1 definition found

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

  disk drive
  floppy disk drive
  floppy drive
  
     <hardware, storage> (Or "hard disk drive", "hard drive",
     "floppy disk drive", "floppy drive") A peripheral device
     that reads and writes hard disks or floppy disks.  The
     drive contains a motor to rotate the disk at a constant rate
     and one or more read/write heads which are positioned over the
     desired track by a servo mechanism.  It also contains the
     electronics to amplify the signals from the heads to normal
     digital logic levels and vice versa.
  
     In order for a disk drive to start to read or write a given
     location a read/write head must be positioned radially over
     the right track and rotationally over the start of the right
     sector.
  
     Radial motion is known as "seeking" and it is this which
     causes most of the intermittent noise heard during disk
     activity.  There is usually one head for each disk surface and
     all heads move together.  The set of locations which are
     accessible with the heads in a given radial position are known
     as a "cylinder".  The "seek time" is the time taken to
     seek to a different cylinder.
  
     The disk is constantly rotating (except for some floppy disk
     drives where the motor is switched off between accesses to
     reduce wear and power consumption) so positioning the heads
     over the right sector is simply a matter of waiting until it
     arrives under the head.  With a single set of heads this
     "rotational latency" will be on average half a revolution
     but some big drives have multiple sets of heads spaced at
     equal angles around the disk.
  
     If seeking and rotation are independent, access time is seek
     time + rotational latency.  When accessing multiple tracks
     sequentially, data is sometimes arranged so that by the time
     the seek from one track to the next has finished, the disk has
     rotated just enough to begin accessing the next track.
  
     See also sector interleave.
  
     The disks may be removable disks; floppy disks always are,
     removable hard disks were common on mainframes and
     minicomputers but less so on microcomputers until the mid
     1990s(?) with products like the Zip Drive.
  
     A CD-ROM drive is not usually referred to as a disk drive.
  
     Two common interfaces for disk drives (and other devices) are
     SCSI and IDE.  ST-506 used to be common in
     microcomputers (in the 1980s?).
  
     (1997-04-15)