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FDC(4)                   BSD Kernel Interfaces Manual                   FDC(4)

NAME
     fdc -- NEC765 compatible floppy disk driver

SYNOPSIS
     fdc0 at isa? port 0x3f0 irq 6 drq 2     (alpha, amd64, i386)
     fdc0 at mainbus0                        (sun4c sparc)
     fdc0 at obio0                           (sun4m sparc)
     fdc* at sbus?                           (sparc64)
     fd* at fdc? flags 0x00

DESCRIPTION
     The fdc driver supports the standard AT floppy disk controllers.  These
     include standard IDE, MFM, RLL, EIDE, ESDI and SCSI controllers with
     floppy attachment, commonly encountered on many isa bus machines, as well
     as the on-board floppy controller found on most sparc and UltraSPARC
     workstations.

     The standard names of a floppy drive will take the form
     /dev/fd{0,1,2,3}{,B,C,D,E,F,G,H}[a-p].

     The first component of this path is the unit number, permitting a total
     of 4 floppy drives.  The next component is missing for the default geome-
     try (it would be A, but it is omitted for simplicity) and B-H for the
     other 7 geometry types the floppy driver supports.  The last component of
     the path is the 16 partitions that a floppy disk can support.

     The additional geometry types are as follows:

           `B' 1.44MB
           `C' 1.2MB
           `D' 360KB/AT (360KB disk in a 1.2 MB drive)
           `E' 360KB/PC (360KB drive)
           `F' 720KB
           `G' 720KB/x (720KB in a 1.2 MB drive)
           `H' 360KB/x (360KB in a 720KB drive)

     The default geometry is the format specified in the BIOS, and is typi-
     cally the largest supported format.

     Some isa floppy controllers do not respond correctly to probes, and the
     configuration file flags field can be used to specify a particular drive
     type, overriding the probed type.  If the 0x10 bit is on, the low order
     three bits of the flags field encode the drive type, as follows:

           1 2.88MB
           2 1.44MB
           3 1.2MB
           4 720K
           5 360K
           6 1.2 MB Japanese format

     If the 0x20 bit is on, the drive will be attached even if it was not
     found by the probe routine.  These flags are ignored on fdc controllers
     not connected to an isa(4) bus.

SEE ALSO
     eject(1), fdformat(1), ebus(4), intro(4), isa(4), sbus(4)

BUGS
     The fdc driver can interfere with other isa(4) controllers, namely some
     WD/SMC network controllers fail to work when the probing mechanism in the
     fdc driver probes for a missing second floppy drive.  In this case you
     should try recompiling the kernel replacing the relevant line with fd0 at
     fdc?.

BSD                             March 28, 2017                             BSD