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FD(4)                      Linux Programmer's Manual                     FD(4)

NAME
       fd - floppy disk device
CONFIGURATION
       Floppy  drives  are  block devices with major number 2.  Typically they
       are owned by root.floppy (i.e.,  user  root,  group  floppy)  and  have
       either  mode  0660  (access checking via group membership) or mode 0666
       (everybody has access).  The minor  numbers  encode  the  device  type,
       drive  number,  and  controller number.  For each device type (that is,
       combination of density and track count) there is a base  minor  number.
       To  this  base number, add the drive's number on its controller and 128
       if the drive is on the secondary controller.  In the  following  device
       tables, n represents the drive number.
       Warning:  If  you  use  formats with more tracks than supported by your
       drive, you may cause it mechanical damage.  Trying once if more  tracks
       than  the  usual  40/80 are supported should not damage it, but no war-
       ranty is given for that.  If you are  not  sure,  don't  create  device
       entries for those formats, so as to prevent their usage.
       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  fol-
       lowing 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 reen-
              able autodetection, you have to issue an FDCLRPRM.
       FDGETDRVTYP
              returns the type of a drive (name parameter).  For formats which
              work in several drive types, FDGETDRVTYP returns a name which is
              appropriate for the oldest drive type which supports  this  for-
              mat.
       FDFLUSH
              invalidates the buffer cache for the given drive.
       FDSETMAXERRS
              sets  the  error  thresholds  for reporting errors, aborting the
              operation, recalibrating, resetting, and reading sector by  sec-
              tor.
       FDSETMAXERRS
              gets the current error thresholds.
       FDGETDRVTYP
              gets the internal name of the drive.
       FDWERRORCLR
              clears the write error statistics.
       FDWERRORGET
              reads  the write error statistics.  These include the total num-
              ber 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 conditions.
       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 floppycontrol(1) manual
       page.
FILES
       /dev/fd*
NOTES
       The various formats permit reading and writing  many  types  of  disks.
       However,  if a floppy is formatted with an inter-sector gap that is too
       small, performance may drop, to the point of needing a few  seconds  to
       access an entire track.  To prevent this, use interleaved formats.
       It  is  not  possible  to  read  floppies which are formatted using GCR
       (group code recording), which is used by Apple II and Macintosh comput-
       ers (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.
SEE ALSO
       chown(1),   floppycontrol(1),  getfdprm(1),  mknod(1),  superformat(1),
       mount(8), setfdprm(8)
COLOPHON
       This page is part of release 3.53 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux                             2010-08-29                             FD(4)