Technical data

SunOS 5.5 Devices fd(7D)
NAME fd, fdc − drivers for floppy disks and floppy disk controllers
SYNOPSIS
SPARC /dev/diskette0
/dev/rdiskette0
x86 /dev/diskette[0-1]
/dev/rdiskette[0-1]
DESCRIPTION The fd driver provides the interfaces to the floppy disks usingthe Intel 82072 on sun4c
systems and the Intel 82077 on sun4m and sun4u systems.
The fd and fdc drivers provide the interfaces to floppy disks using the Intel 8272, Intel
82077, NEC 765, or compatible disk controllers on x86 systems.
The default partitions for the floppy driver are:
a All cylinders except the last
b Only the last cylinder
c Entire diskette
The fd driver autosenses the density of the diskette.
When the floppy is first opened the driver looks for a SunOS label in logical block 0 of the
diskette. If attempts to read the SunOS label fail, the open will fail. If block 0 is read suc-
cessfully but a SunOS label is not found, auto-sensed geometry and default partitioning
are assumed.
The fd driver supports both block and raw interfaces. The block files access the diskette
using the system’s normal buffering mechanism and may be read and written without
regard to physical diskette records. There is also a “raw” interface that provides for
direct transmission between the diskette and the user’s read or write buffer. A single
read(2) or write(2) call usually results in one I/O operation; therefore raw I/O is consid-
erably more efficient when many words are transmitted.
3.5" Diskettes For 3.5" double-sided diskettes, the following densities are supported:
SPARC 1.7 Mbyte density 80 cylinders, 21 sectors per track, 1.7 Mbyte capacity
high density 80 cylinders, 18 sectors per track, 1.44 Mbyte capacity
double density 80 cylinders, 9 sectors per track, 720 Kbyte capacity
medium density 77 cylinders, 8 sectors per track, 1.2 Mbyte capacity
(sun4m and sun4u only)
x86 extended density 80 cylinders, 36 sectors per track, 2.88 Mbyte capacity
1.7 Mbyte density 80 cylinders, 21 sectors per track, 1.7 Mbyte capacity
high density 80 cylinders, 18 sectors per track, 1.44 Mbyte capacity
double density 80 cylinders, 9 sectors per track, 760 Kbyte capacity
medium density 77 cylinders, 8 sectors per track, 1.2 Mbyte capacity
(requires appropriate hardware; see NOTES)
modified 25 Aug 1995 7D-111