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Linux 2.6 - man page for fd (linux section 4)

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

       fd - floppy disk device

       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, combina-
       tion  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 warranty is given for that.  If you are not sure, don't cre-
       ate 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

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

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

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

	      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 autode-
	      tection.	In order to reenable autodetection, you have to issue an FDCLRPRM.

	      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 format.

	      invalidates the buffer cache for the given drive.

	      sets the error thresholds for reporting errors, aborting the operation, recalibrat-
	      ing, resetting, and reading sector by sector.

	      gets the current error thresholds.

	      gets the internal name of the drive.

	      clears the write error statistics.

	      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.

	      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.

	      sets various drive parameters.

	      reads these parameters back.

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

	      polls the drive and return its state.

	      gets the floppy controller state.

	      resets the floppy controller under certain conditions.

	      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.


       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  inter-
       leaved formats.

       It  is not possible to read floppies 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.

       chown(1), floppycontrol(1), getfdprm(1), mknod(1), superformat(1), mount(8), setfdprm(8)

       This  page  is  part of release 3.55 of the Linux man-pages project.  A description of the
       project,    and	  information	 about	  reporting    bugs,	can    be    found     at

Linux					    2010-08-29					    FD(4)

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