资料来源 : pyDict

磁盘驱动器

资料来源 : WordNet®

disk drive
     n : computer hardware that holds and spins a magnetic or optical
         disk and reads and writes information on it [syn: {disc
         drive}, {hard drive}, {Winchester drive}]

资料来源 : Free On-Line Dictionary of Computing

disk drive
     
         (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 "{seek}ing" 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}.  {ST506} used to be common in microcomputers
        (in the 1980s?).
     
        (1997-04-15)