fd — floppy disk device
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.
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 |
fd special files
access the floppy disk drives in raw mode. The following
ioctl(2) calls are
supported by fd
devices:
FDCLRPRMclears the media information of a drive (geometry of disk in drive).
FDSETPRMsets the media information of a drive. The media information will be lost when the media is changed.
FDDEFPRMsets 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.
FDGETDRVTYPreturns 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.
FDFLUSHinvalidates the buffer cache for the given drive.
FDSETMAXERRSsets the error thresholds for reporting errors, aborting the operation, recalibrating, resetting, and reading sector by sector.
FDSETMAXERRSgets the current error thresholds.
FDGETDRVTYPgets the internal name of the drive.
FDWERRORCLRclears the write error statistics.
FDWERRORGETreads 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.
FDTWADDLESwitch the drive motor off for a few microseconds. This might be needed in order to access a disk whose sectors are too close together.
FDSETDRVPRMsets various drive parameters.
FDGETDRVPRMreads these parameters back.
FDGETDRVSTATgets the cached drive state (disk changed, write protected et al.)
FDPOLLDRVSTATpolls the drive and return its state.
FDGETFDCSTATgets the floppy controller state.
FDRESETresets the floppy controller under certain conditions.
FDRAWCMDsends 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.
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.
chown(1), floppycontrol(1), getfdprm(1), mknod(1), superformat(1), mount(8), setfdprm(8)
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t Copyright (c) 1993 Michael Haardt (michaelcantor.informatik.rwth-aachen.de) and 1994,1995 Alain Knaff (Alain.Knaffimag.fr) This is free documentation; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The GNU General Public License's references to "object code" and "executables" are to be interpreted as the output of any document formatting or typesetting system, including intermediate and printed output. This manual is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this manual; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA. Modified, Sun Feb 26 15:00:02 1995, faithcs.unc.edu |