Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
FDCONTROL(8)		FreeBSD	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 re-
     quire 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 re-
     port the drive type that is registered with the device driver.  In	the
     shortest form, a single string describing the drive type will be re-
     turned.  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
     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:
	   KB	  sectrac   secsize   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:
	   KB	  sectrac   secsize    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:
	   KB	 sectrac   secsize   ncyls   speed   heads   flags
	   720	 9	   2 (512)   80	     250     2	     MFM

     360K drives:
	   KB	 sectrac   secsize   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 Jorg Wunsch, Dresden.

FreeBSD	13.0			 April 7, 2017			  FreeBSD 13.0


Want to link to this manual page? Use this URL:

home | help