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FDCONTROL(8)              BSD System Manager's Manual             FDCONTROL(8)

     fdcontrol -- display and modify floppy disk parameters

     fdcontrol [-F] [-d dbg] [-f fmt] [-s fmtstr] [-v] device

     The fdcontrol utility allows the modification of the run-time behavior of
     the fdc(4) driver for the device specified by device.

     Commands are implemented to query the current device density settings as
     well as the underlying device hardware as registered with the driver, to
     manipulate debugging levels, and to adjust the device density settings.
     All the operations that manipulate the kernel settings are restricted to
     the superuser (by the device driver), while all inquiry requests only
     require read access to device.

     The device argument should always be given as a full path name, e.g.

   Inquiry Commands
     Running the fdcontrol utility without any of the optional flags will
     report the drive type that is registered with the device driver.  In the
     shortest form, a single string describing the drive type will be
     returned.  Possible values are: ``360K'', ``1.2M'', ``720K'', ``1.44M'',
     ``2.88M'', or ``unknown''.  This information is primarily intended to be
     easily parsable by scripts.

     In order to add some descriptive text that makes the output better human
     readable, the flag -v can be added.

     Specifying flag -F will report the device's density settings in a form
     that is suitable as input to the -s fmtstr option (see below).  Again,
     together with -v, some more text will be returned, including the total
     capacity of the density settings in kilobytes.

   Debug Control
     If the fdc(4) driver was configured with the FDC_DEBUG option, by
     default, device debugging information is still disabled since it could
     produce huge amounts of kernel messages.  It needs to be turned on using
     fdcontrol together with ``-d 1'', usually immediately before starting an
     operation on the respective device the debug information is wanted for,
     and later turned off again using ``-d 0''.  Note that debugging levels
     are a driver's global option that will affect any drives and controllers
     using the fdc(4) driver, regardless which device was specified on the
     fdcontrol command line.

   Density Control
     The fdc(4) control utilities support two different options how to specify
     device density settings.  The first form uses -f fmt to specify the for-
     mat of the medium in kilobytes.  Depending on the underlying drive type,
     the value is compared against a table of known commonly used device den-
     sity settings for that drive, and if a match is found, those settings
     will be used.  Currently, the following values for the respective drive
     types are acceptable:

     2.88M and 1.44M drives:
           lB lB lB lB lB lB lB r l l l l l l.  KB   sectrac   sec-
           size   ncyls     speed     heads     flags 1721 21   2
           (512)   82   500  2    MFM 1476 18   2 (512)   82   500  2    MFM
           1440 18   2 (512)    80   500  2    MFM 1200 15   2
           (512)   80   500  2    MFM 820  10   2 (512)   82   250  2    MFM
           800  10   2 (512)    80   250  2    MFM 720  9    2
           (512)   80   250  2    MFM

     1.2M drives:
           lB lB lB lB lB lB lB r l l l l l l.  KB   sectrac   sec-
           size   ncyls     speed     heads     flags 1200 15   2
           (512)   80   500  2    MFM 1232 8    3 (1024)  77   500  2    MFM
           1476 18   2 (512)    82   500  2    MFM 1440 18   2
           (512)   80   500  2    MFM 1200 15   2 (512)   80   500  2    MFM
           820  10   2 (512)    82   300  2    MFM 800  10   2
           (512)   80   300  2    MFM 720  9    2 (512)   80   300  2    MFM
           360  9    2 (512)    40   300  2    MFM,2STEP 640  8    2
           (512)   80   300  2    MFM

     720K drives:
           lB lB lB lB lB lB lB r l l l l l l.  KB   sectrac   sec-
           size   ncyls     speed     heads     flags 720  9    2
           (512)   80   250  2    MFM

     360K drives:
           lB lB lB lB lB lB lB r l l l l l l.  KB   sectrac   sec-
           size   ncyls     speed     heads     flags 360  9    2
           (512)   40   250  2    MFM

     The second form to specify a device density uses -s fmtstr to explicitly
     specify each parameter in detail.  The argument fmtstr is a comma-sepa-
     rated list of values of the form:


     The meaning of the parameters is:

     sectrac  The number of sectors per track.

     secsize  The sector size code, 0 = 128 bytes (or less), 1 = 256 bytes, 2
              = 512 bytes, 3 = 1024 bytes.

     datalen  The actual sector size if the size code is 0, or the (ignored)
              value 0xFF for larger size codes.

     gap      The length of the gap 3 parameter for read/write operations.

     ncyls    The number of cylinders.

     speed    The transfer speed in kilobytes per second.  Can be 250, 300,
              500, or 1000, but each drive type only supports a subset of
              these values.

     heads    The number of heads.

     f_gap    The length of the gap 3 when formatting media.

     f_inter  The sector interleave to be applied when formatting.  0 means no
              interleave, 1 means 1:1 etc.

     offs2    The offset of the sector numbers on side 2 (i.e., head number
              1).  Normally, sector numbering on both sides starts with 1.

     flags    A list from one of the following flag values:

              +mfm      Use MFM encoding.
              -mfm      Use FM (single-density) encoding.
              +2step    Use 2 steps per each cylinder (for accessing 40-cylin-
                        der media in 80-cylinder drives).
              -2step    Do not use 2 steps per cylinder, i.e., access each
                        physical cylinder of the drive.
              +perpend  Use perpendicular recording (for 2.88 MB media, cur-
                        rently not supported).
              -perpend  Use longitudinal recording.

     For any missing parameter, the current value will be used, so only actual
     changes need to be specified.  Thus to turn off a flag bit (like +mfm
     which is the default for all drive types), the form with a leading minus
     sign must explicitly be used.

     A simple inquiry about the drive type:

           $ fdcontrol /dev/fd0

     Same as above, but with verbose output.  Note that the result is about
     the drive type, as opposed to a device density, so it is independent from
     the actual subdevice being used for device.

           $ fdcontrol -v /dev/fd0
           /dev/fd0: 1.44M drive (3.5" high-density)

     Inquiry about the density settings:

           $ fdcontrol -F /dev/fd0

     The verbose flag makes this human readable:

           /dev/fd0: 1440 KB media type
                   Format:         18,512,0xff,0x1b,80,500,2,0x6c,1,0,+mfm
                   Sector size:    512
                   Sectors/track:  18
                   Heads/cylinder: 2
                   Cylinders/disk: 80
                   Transfer rate:  500 kbps
                   Sector gap:     27
                   Format gap:     108
                   Interleave:     1
                   Side offset:    0
                   Flags           <MFM>

     As indicated, trailing commas in the parameter list may be omitted.

     In order to access archaic 160 KB single-density (FM encoded) 5.25 media
     in a modern 1.2M drive, something like the following definition would be
     needed.  (Note that not all controller hardware is actually capable of
     handling FM encoding at all.)

     # fdcontrol -s 16,128,0x80,0x2,40,300,,0x10,,,-mfm,+2step /dev/fd1.1

     It is still possible to hook up 8" drives to most modern floppy con-
     trollers, given the right cable magic.  (On PC hardware, tell the BIOS
     that it is a 5.25" drive.)  The classical 128/26/2/77 format can be read
     with this entry

           fdcontrol -s  26,128,0x80,0x2,77,500,2,0x10,,,-mfm /dev/fd0


     The fdcontrol utility appeared in FreeBSD 2.0, and was vastly overhauled
     in FreeBSD 5.0.

     The program and this man page was contributed by Jrg Wunsch, Dresden.

BSD                            December 25, 2001                           BSD