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, combination 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.
Don't create device
entries for those formats to prevent their usage if you are not sure.
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
DESCRIPTION
fd special files access the floppy disk drives in raw mode.
The following
ioctl(2)
calls are supported by fd devices:
FDCLRPRM
clears the media information of a drive (geometry of disk in drive).
FDSETPRM
sets the media information of a drive.
The media information will be
lost when the media is changed.
FDDEFPRM
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 autodetection.
In order to re-enable autodetection, you
have to issue an FDCLRPRM.
FDGETDRVTYP
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.
FDFLUSH
invalidates the buffer cache for the given drive.
FDSETMAXERRS
sets the error thresholds for reporting errors, aborting the operation,
recalibrating, resetting, and reading sector by sector.
FDSETMAXERRS
gets the current error thresholds.
FDGETDRVTYP
gets the internal name of the drive.
FDWERRORCLR
clears the write error statistics.
FDWERRORGET
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.
FDTWADDLE
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.
FDSETDRVPRM
sets various drive parameters.
FDGETDRVPRM
reads these parameters back.
FDGETDRVSTAT
gets the cached drive state (disk changed, write protected et al.)
FDPOLLDRVSTAT
polls the drive and return its state.
FDGETFDCSTAT
gets the floppy controller state.
FDRESET
resets the floppy controller under certain conditions.
FDRAWCMD
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 manual page for
floppycontrol.
FILES
/dev/fd*
NOTES
The various formats allow to read and write many types of disks.
However, if a floppy is formatted with a too small inter sector gap,
performance may drop, up to needing a few seconds to access an entire
track.
To prevent this, use interleaved 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.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
