fdcontrol(8)

NAME

fdcontrol - display and modify floppy disk parameters

SYNOPSIS

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

DESCRIPTION

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 densi
ty settings. All the operations that manipulate the kernel settings are
restricted to the superuser (by the device driver), while all inquiry re
quests only require read access to device.
The device argument should always be given as a full path
name, e.g. /dev/fd0.
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 be; low). 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 op; tion, 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 debug; ging levels
are a driver's global option that will affect any drives and; controllers
using the fdc(4) driver, regardless which device was speci; fied 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 format of the medium in kilobytes. Depending on the underlying; drive type,
the value is compared against a table of known commonly used; device density settings for that drive, and if a match is found, those; settings
will be used. Currently, the following values for the re; spective 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-separated list of values of the form:
sectrac,secsize,datalen,gap,ncyls,speed,heads,f_gap,f_inter,offs2,flags
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 for
matting. 0: means no interleave, 1 means 1:1 etc.
offs2 The offset of the sector numbers on side 2
(i.e., head num: ber 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-cylinder 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, currently 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.

EXAMPLES

A simple inquiry about the drive type:: $ fdcontrol /dev/fd0
1.44M
Same as above, but with verbose output. Note that the re
sult is about the drive type, as opposed to a device density, so it is in
dependent 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
18,512,0xff,0x1b,80,500,2,0x6c,1,0,+mfm
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 encod
ed) 5.25 media in a modern 1.2M drive, something like the following defini
tion 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 controllers, 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

HISTORY

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

AUTHORS

The program and this man page was contributed by Jorg Wun
sch, Dresden.
BSD December 25, 2001

docs.sk

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See also