fd - Floppy disk interface
controller fdi0 at * vector fdintr device
disk fd0 at fdi0 drive 0 device disk
fd1 at fdi0 drive 1
The fd device driver and fdi controller make up the interface
to the integrated Floppy Disk Interface (FDI).
If the minor number is less than 64, the driver select
number is indicated by bits 4 and 5, and the partition by
bits 0 through 3. If the minor number is one of 64, 65,
66, or 67, the drive select number is indicated by bits 0
and 1, and disk partitions are disabled. In the latter
case, the entire surface of the media is treated as one
large partition, and attempts to change the partition
table fail. The major number is 14 for both the block
interface and the raw (character) interface.
Legacy Device Names [Toc] [Back]
Refer to System Administration for an explanation of
device naming.
The legacy device names have the format rfd0, which indicates
the raw device interface, or fd0p, which indicates
the block interface and where p indicates the partition
using the characters a through h. If you do not specify a
partition with the block interface, partitioning is disabled.
Default file protection for /dev/fd0 is 666.
Current Device Special File Names [Toc] [Back]
The current device special file names are
/dev/disk/floppy, /dev/disk/floppy0c, and
/dev/disk/floppy0a. The raw current device special file
names are /dev/rdisk/floppy, /dev/rdisk/floppy0c, and
/dev/rdisk/floppy0a. These device names are created automatically
by dsfmgr when the system starts up.
Interface [Toc] [Back]
The block interface is restricted to 512-byte, disk-sector
aligned accesses. Reads or writes that attempt to start
at the middle of a sector actually start at the beginning
of the sector.
There is no sector-boundary limitation if you use the raw
interface.
The driver protects the process that opens the floppy disk
device from an accidental media change by preventing
access to the device if the media is removed and then
reinserted. To access the drive after the media has been
changed, either you must close and then reopen the device,
or you must issue a DEVIOCGET or FDIOTPRRST ioctl. You can
use the fddisk command with the -new option to issue the
FDIOTPRRST ioctl.
When a floppy disk device is first opened after changing
media, a delay occurs while the partition table is read
from the media if the device is not of type rfd0 or
/dev/rdisk/floppy0. If the device is opened with FNDELAY,
partition table reading may be delayed until the first
actual read or write request.
If you access media containing non-UFS data, the data on
the media may appear to be a valid partition table. In
this case, the user will probably not be able to access
the media. To work around the problem, use the rfd0
device.
Partitions a and c begin at physical sector 0 and occupy
the entire disk. All other partitions also begin at physical
sector 0, but are of zero (0) length. You can change
partition sizes by using the disklabel command.
The currently supported floppy disk drive is the RX26. The
supported media types in the RX26 are the 350DD of size
737280 (1440 sectors), 350HD of size 1474560 (2880 sectors),
and 350ED of size 2949120 (5760 sectors), as shown
in the following partition layouts for the media types:
RX26, Double Density:
disk start length
dsk?a 0 1440
dsk?b 0 0
dsk?c 0 1440
dsk?d 0 0
dsk?e 0 0
dsk?f 0 0
dsk?g 0 0
dsk?h 0 0
RX26, High Density:
disk start length
dsk?a 0 2880
dsk?b 0 0
dsk?c 0 2880
dsk?d 0 0
dsk?e 0 0
dsk?f 0 0
dsk?g 0 0
dsk?h 0 0
RX26, Extra Density:
disk start length
dsk?a 0 5760
dsk?b 0 0
dsk?c 0 5760
dsk?d 0 0
dsk?e 0 0
dsk?f 0 0
dsk?g 0 0
dsk?h 0 0
Ioctl Support [Toc] [Back]
Several special ioctls are defined for use with the fd
device driver. Use of these requires that
/usr/include/sys/ioctl.h and /sys/io/fd/mips/fdi.h are
included. See the fdi.h file for reference purposes.
FDIOSENSE returns information about the current state of
the drive via the structure fd_sense. All elements of
this structure are initialized by this call. See comments
in fdi.h for use of each element.
FDIOGETMTYP returns information about the media currently
in the drive via the structure fd_mt. All elements of
this structure are initialized by this call. See comments
in fdi.h for use of each element.
FDIOFMTDSK, FDIOFFBSETUP, FDIOFFBNEXT, and FDIOFMTTRK are
used for disk formatting. Data is passed to and from these
calls via certain elements of a structure of type
fd_fmt_spec. See comments in fdi.h for use of each element.
FDIOFMTDSK causes the entire disk to be formatted.
FDIOFMTTRK causes a specified track to be formatted. The
combination of FDIOFFBSETUP and FDIOFFBNEXT cause the
entire disk to be formatted, a little at a time, allowing
the calling process to display an updated status line
indicating the progress of the format.
FDIOTPRRST causes the driver to ignore the fact that the
media might have just been removed and reinserted. Status
information is returned via a fd_sense structure, just as
with the FDIOSENSE call.
FDIOSEEK allows the user to specify the position of the
next single-sector access (and only the next access) in
any of several formats. These formats include logicalsector-number
format, physical-sector-number format, and
cylinder-head-sector format. These formats are specified
in a structure of type fd_seek. See comments in fdi.h for
use of each element.
FDIOMKCHS and FDIOMKPSN are used to translate between
cylinder-head-sector sector specification and physicalsector-number
sector specification. Data is passed to and
from these calls via certain elements of a structure of
type fd_chs_psn. See comments in fdi.h for use of each
element.
The calls DEVIOCGET, DEVGETGEOM, DIOCGETPT, DIOCDGTPT, and
DIOCSETPT are also supported and perform in their expected
manner. A call to DEVIOCGET also has the effect of calling
FDIOTPRRST.
/dev/fd0
/dev/rfd0
/dev/disk/floppy*
/dev/rdisk/floppy*
Commands: disklabel(8), dsfmgr(8), mtools(1), dxmtools(1)
fddisk(8), MAKEDEV(8), uerf(8)
fd(7)
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