FDC(4)                    OpenBSD Programmer's Manual                   FDC(4)

NAME
     fdc - NEC765 compatible floppy disk driver

SYNOPSIS
     fdc0 at isa? port 0x3f0 irq 6 drq 2
     fd* at fdc? drive ? flags Z

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.

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

     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 typical-
     ly the largest supported format.

     Some floppy controllers do not respond correctly to probes, and the con-
     figuration 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.

SEE ALSO
     intro(4), dmesg(8)

BUGS
     The fdc driver can interfere with other 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? drive ?.

OpenBSD 2.9                     March 25, 1996                               1
