freebsd-skq/usr.sbin/fdcontrol/fdcontrol.8

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.Dd April 7, 2017
.Dt FDCONTROL 8
.Os
.Sh NAME
.Nm fdcontrol
.Nd display and modify floppy disk parameters
.Sh SYNOPSIS
.Nm
.Op Fl F
.Op Fl d Ar dbg
.Op Fl f Ar fmt
.Op Fl s Ar fmtstr
.Op Fl v
.Ar device
.Sh DESCRIPTION
The
.Nm
utility allows the modification of the run-time behavior of the
.Xr fdc 4
driver for the device specified by
.Ar device .
.Pp
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
.Ar device .
.Pp
The
.Ar device
argument should always be given as a full path name, e.g.\&
.Pa /dev/fd0 .
.Ss Inquiry Commands
Running the
.Nm
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:
.Dq Li 360K ,
.Dq Li 1.2M ,
.Dq Li 720K ,
.Dq Li 1.44M ,
.Dq Li 2.88M ,
or
.Dq Li unknown .
This information is primarily intended to be easily parsable by
scripts.
.Pp
In order to add some descriptive text that makes the output better
human readable, the flag
.Fl v
can be added.
.Pp
Specifying flag
.Fl F
will report the device's density settings in a form that is suitable
as input to the
.Fl s Ar fmtstr
option (see below).
Again, together with
.Fl v ,
some more text will be returned, including the total capacity of the
density settings in kilobytes.
.Ss Debug Control
The
.Xr fdc 4
control utilities support two different options how to specify device
density settings.
The first form uses
.Fl f Ar 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 respective drive types are acceptable:
.Bl -item
.It
2.88M and 1.44M drives:
.Bd -ragged -offset indent -compact
.TS
lB lB lB lB lB lB lB
r l l l l l l.
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
.TE
.Ed
.It
1.2M drives:
.Bd -ragged -offset indent -compact
.TS
lB lB lB lB lB lB lB
r l l l l l l.
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
.TE
.Ed
.It
720K drives:
.Bd -ragged -offset indent -compact
.TS
lB lB lB lB lB lB lB
r l l l l l l.
KB	sectrac	secsize	ncyls	speed	heads	flags
720	9	2 (512)	80	250	2	MFM
.TE
.Ed
.It
360K drives:
.Bd -ragged -offset indent -compact
.TS
lB lB lB lB lB lB lB
r l l l l l l.
KB	sectrac	secsize	ncyls	speed	heads	flags
360	9	2 (512)	40	250	2	MFM
.TE
.Ed
.El
.Pp
The second form to specify a device density uses
.Fl s Ar fmtstr
to explicitly specify each parameter in detail.
The argument
.Ar fmtstr
is a comma-separated list of values of the form:
.Pp
.Sm off
.Ar sectrac , secsize , datalen , gap , ncyls , speed ,
.Ar heads , f_gap , f_inter , offs2 , flags
.Sm on
.Pp
The meaning of the parameters is:
.Bl -tag -width ".Ar secsize"
.It Ar sectrac
The number of sectors per track.
.It Ar secsize
The sector size code, 0 = 128 bytes (or less), 1 = 256 bytes, 2 = 512
bytes, 3 = 1024 bytes.
.It Ar datalen
The actual sector size if the size code is 0, or the (ignored) value
0xFF for larger size codes.
.It Ar gap
The length of the gap 3 parameter for read/write operations.
.It Ar ncyls
The number of cylinders.
.It Ar 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.
.It Ar heads
The number of heads.
.It Ar f_gap
The length of the gap 3 when formatting media.
.It Ar f_inter
The sector interleave to be applied when formatting.
0 means no
interleave, 1 means 1:1 etc.
.It Ar offs2
The offset of the sector numbers on side 2 (i.e., head number 1).
Normally, sector numbering on both sides starts with 1.
.It Ar flags
A list from one of the following flag values:
.Pp
.Bl -tag -width ".Cm +perpend" -compact
.It Cm +mfm
Use MFM encoding.
.It Cm -mfm
Use FM (single-density) encoding.
.It Cm +2step
Use 2 steps per each cylinder (for accessing 40-cylinder media in
80-cylinder drives).
.It Cm -2step
Do not use 2 steps per cylinder, i.e., access each physical cylinder
of the drive.
.It Cm +perpend
Use perpendicular recording (for 2.88 MB media, currently not
supported).
.It Cm -perpend
Use longitudinal recording.
.El
.El
.Pp
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
.Cm +mfm
which is the default for all drive types), the form with a leading
minus sign must explicitly be used.
.Sh EXAMPLES
A simple inquiry about the drive type:
.Bd -literal -offset indent
$ fdcontrol /dev/fd0
1.44M
.Ed
.Pp
Same as above, but with verbose output.
Note that the result is about
the
.Em "drive type" ,
as opposed to a
.Em "device density" ,
so it is independent from the actual subdevice being used for
.Ar device .
.Bd -literal -offset indent
$ fdcontrol -v /dev/fd0
/dev/fd0: 1.44M drive (3.5" high-density)
.Ed
.Pp
Inquiry about the density settings:
.Bd -literal -offset indent
$ fdcontrol -F /dev/fd0
18,512,0xff,0x1b,80,500,2,0x6c,1,0,+mfm
.Ed
.Pp
The verbose flag makes this human readable:
.Bd -literal -offset indent
/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>
.Ed
.Pp
As indicated, trailing commas in the parameter list may be omitted.
.Pp
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.)
.Bd -literal
# fdcontrol -s 16,128,0x80,0x2,40,300,,0x10,,,-mfm,+2step /dev/fd1.1
.Ed
.Pp
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
.Bd -literal -offset indent
fdcontrol -s  26,128,0x80,0x2,77,500,2,0x10,,,-mfm /dev/fd0
.Ed
.Sh SEE ALSO
.Xr fdc 4
.Sh HISTORY
The
.Nm
utility appeared in
.Fx 2.0 ,
and was vastly overhauled in
.Fx 5.0 .
.Sh AUTHORS
The program and this man page was contributed by
.An J\(:org Wunsch ,
Dresden.