FDC(4)

NAME
fdc - PC architecture floppy disk controller driver

SYNOPSIS
device fdc0 at isa? port IO_FD1 flags 0x1 irq 6 drq 2
device fd0 at fdc0 drive 0
device fd1 at fdc0 drive 1

DESCRIPTION
This driver provides access to floppy disk drives and QIC40/80 tapedrives. In /dev for each floppy device a number of minor devices are present. The /dev/fd* devices with trailing alphabetic characters are used to indicate ‘partitions’ on the floppy disk. The /dev/fd*.<number> are devices that indicate the size of the floppy disk (so: 720kB, 1440kB etc). The latter are used for formatting disks using fdformat or for accessing different density disks in multidensity drive. Example: 720kB disk in a 1.44Mb drive.

Normally, the driver will ask the system's CMOS memory to obtain the floppy drive configuration. Some machines do not store any form of a configuration value in their CMOS. Use the flags value ‘0x1’ to pretend a 1.44 MB floppy drive as the first unit, without asking the CMOS for it.

Normally, the device driver detects FDC chipsets that have an internal FIFO, and enables the FIFO on them. There is a slight chance that this feature is actually misdetected (seen on an IBM Thinkpad 755c), so it can be turned off using flags ‘0x4’.

FILES
/dev/fd*
    floppy disk device nodes
/dev/fd*.<size in kB>
    floppy disk device nodes where the trailing number indicates the floppy capacity
/sys/config/X86_64_GENERIC
    sample generic kernel config file
/sys/dev/disk/fd/fd.c
    floppy driver source

SEE ALSO
fdformat(1), disktab(5)