fd

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NAME

       fd - floppy disk device


CONFIGURATION

       Floppy drives are block devices with major number 2.  Typ-
       ically they are owned by root.floppy and have either  mode
       0660  (access  checking via group membership) or mode 0666
       (everybody has access).  For the following devices,  n  is
       the  drive number.  It is 0 for the first drive, 1 for the
       second etc.  To get a minor number for  a  specific  drive
       connected to the first controller, add n to the minor base
       number.  If it is connected to the second controller,  add
       n+128  to the minor base number.  Warning: If you use for-
       mats with more tracks than supported by  your  drive,  you
       may  damage  it  mechanically.  Trying once if more tracks
       than the usual 40/80 are supported should not  damage  it,
       but  no  warranty  is given for that.  Don't create device
       entries for those formats to prevent their  usage  if  you
       are not sure.

       Drive  independent device files which automatically detect
       the media format and capacity:

       Name   Base minor #
       --------------------
       fdn    0

       5.25 inch double density device files:

       Name         Capac.   Cyl.   Sect.   Heads   Base minor #
       ----------------------------------------------------------
       fdnd360      360K     40     9       2       4

       5.25 inch high density device files:

       Name         Capac.   Cyl.   Sect.   Heads   Base minor #
       ----------------------------------------------------------
       fdnh360      360K     40     9       2       20
       fdnh410      410K     41     10      2       48
       fdnh420      420K     42     10      2       64
       fdnh720      720K     80     9       2       24
       fdnh880      880K     80     11      2       80
       fdnh1200     1200K    80     15      2       8
       fdnh1440     1440K    80     18      2       40
       fdnh1476     1476K    82     18      2       56
       fdnh1494     1494K    83     18      2       72
       fdnh1600     1600K    80     20      2       92

       3.5 inch double density device files:

       Name         Capac.   Cyl.   Sect.   Heads   Base minor #
       ----------------------------------------------------------
       fdnD360      360K     80     9       1       12

       fdnD720      720K     80     9       2       16
       fdnD800      800K     80     10      2       120
       fdnD1040     1040K    80     13      2       84
       fdnD1120     1120K    80     14      2       88

       3.5 inch high density device files:

       Name         Capac.   Cyl.   Sect.   Heads   Base minor #
       ----------------------------------------------------------
       fdnH360      360K     40     9       2       12
       fdnH720      720K     80     9       2       16
       fdnH820      820K     82     10      2       52
       fdnH830      830K     83     10      2       68
       fdnH1440     1440K    80     18      2       28
       fdnH1600     1600K    80     20      2       124
       fdnH1680     1680K    80     21      2       44
       fdnH1722     1722K    82     21      2       60
       fdnH1743     1743K    83     21      2       76
       fdnH1760     1760K    80     22      2       96
       fdnH1840     1840K    80     23      2       116
       fdnH1920     1920K    80     24      2       100

       3.5 inch extra density device files:

       Name         Capac.   Cyl.   Sect.   Heads   Base minor #
       ----------------------------------------------------------
       fdnE2880     2880K    80     36      2       32
       fdnCompaQ    2880K    80     36      2       36
       fdnE3200     3200K    80     40      2       104
       fdnE3520     3520K    80     44      2       108
       fdnE3840     3840K    80     48      2       112


DESCRIPTION

       fd special files access the  floppy  disk  drives  in  raw
       mode.   The  following  ioctl(2) calls are supported by fd
       devices:

       FDCLRPRM
              clears the media information of a  drive  (geometry
              of disk in drive).

       FDSETPRM
              sets  the  media  information of a drive. The media
              information will be lost when the media is changed.

       FDDEFPRM
              sets  the media information of a drive (geometry of
              disk in drive). The media information will  not  be
              lost  when  the media is changed. This will disable
              autodetection. In order to re-enable autodetection,
              you have to issue an FDCLRPRM .

       FDGETDRVTYP
              displays the type of a drive (name parameter).  For
              formats which work in several drive  types,  FDGET-
              DRVTYP  returns a name which is appropriate for the
              oldest drive type which supports this format.

       FDFLUSH
              invalidates the buffer cache for the given drive.

       FDFLUSH
              invalidates the buffer cache for the given drive.

       FDSETMAXERRS
              sets the  error  tresholds  for  reporting  errors,
              aborting  the  operation, recalibrating, resetting,
              and reading sector by sector.

       FDSETMAXERRS
              gets the current error tresholds.

       FDGETDRVTYP
              gets the internal name of the drive.

       FDWERRORCLR
              clears the write error statistics.

       FDWERRORGET
              reads the write error statistics. These include the
              total number of write errors, the location and disk
              of the first write error, and the location and disk
              of  the last write error. Disks are identified by a
              generation number which is incremented at  (almost)
              each disk change.

       FDTWADDLE
              Switch  the drive motor off for a few microseconds.
              This might be needed in  order  to  access  a  disk
              whose sectors are too close together.

       FDSETDRVPRM
              sets various drive parameters.

       FDGETDRVPRM
              reads these parameters back.

       FDGETDRVSTAT
              gets  the  cached  drive state (disk changed, write
              protected et al.)

       FDPOLLDRVSTAT
              polls the drive and return its state.

       FDGETFDCSTAT
              gets the floppy controller state.


       FDRESET
              resets the floppy controller under  certain  condi-
              tions.

       FDRAWCMD
              sends a raw command to the floppy controller.

       For   more   precise   information,   consult   also   the
       <linux/fd.h> and <linux/fdreg.h> include files, as well as
       the manual page for floppycontrol.


NOTES

       The  various formats allow to read and write many types of
       disks.  However, if a floppy is formatted with a too small
       inter  sector  gap,  performance may drop, up to needing a
       few seconds to access an entire track.  To  prevent  this,
       use  interleaved formats. It is not possible to read flop-
       pies which are formatted using GCR (group code recording),
       which  is  used  by Apple II and Macintosh computers (800k
       disks).  Reading floppies which  are  hard  sectored  (one
       hole  per  sector,  with  the  index  hole  being a little
       skewed) is not supported.  This used  to  be  common  with
       older 8 inch floppies.


FILES

       /dev/fd*


AUTHORS

       Alain    Knaff    (Alain.Knaff@imag.fr),    David    Niemi
       (niemidc@clark.net), Bill Broadhurst  (bbroad@netcom.com).


SEE ALSO

       floppycontrol(1),  mknod(1), chown(1), getfdprm(1), super-
       format(1), mount(8), setfdprm(8)
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