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    Length: 1806 (0x70e)
    Types: TextFile
    Notes: UNIX file
    Names: »fd.4«

└─⟦26887b7e0⟧ Bits:30009717 Comet 32 harddisk image
    └─⟦28c352965⟧ »/a« UNIX Filesystem
        └─⟦this⟧ »usr/man/man4/fd.4« 

TextFile

.ig
	@(#) fd.4	7/14/85
	@(#)Copyright (C) 1985 by Enea Data Svenska AB
..
.TH FD 4
.SH NAME
fd \- floppy driver interface
.SH DESCRIPTION
The files
.I "flop, rflop, flop1, rflop1"
(etc) refer to the floppy driver units 0, 1 (etc).
These can be accessed like any other files,
except that reads and writes of the raw units (names beginning
with "r") must be in multiples of page size (512 bytes)
and the buffers used must be page\-aligned.
In addition, certain IO control functions are available
from the command level using
.IR fdc (1)
and from C programs using
.IR ioctl (2)
as follows:
.LP
#include <sys/fdio.h>
.br
ioctl(fd, command, parameters);
.LP
Here fd is a file descriptor returned from an open() call
to a raw floppy device.
Commands and parameters are explained in the include file
<sys/fdio.h>.
Data to and from diskettes can be copied using the
buffered copy program
.IR bcp (N)
or in a more structured fashion using the floppy archiver
.IR far (1).
.LP
The floppy driver shares the MPS-1604 card with the printer,
they can however be used at the same time.
Should the system ever hang here, the card and (at least) the
floppy driver states can be reset using
.I fdc.
.LP
Reads and writes to a diskette go through the system's
buffered IO mechanism and are not interruptible from the
keyboard except between operations (a fraction of a second normally).
IO control on the other hand specifically "sleeps" at
a low enough priority to be interruptible since having the
terminal "hang" during such operations is annoying.
Programs using it should therefore catch
SIGINT and SIGTERM and either ignore them or execute FDIORESET
before exiting or (possibly) fork and leave behind a copy
to complete the operation.
.SH FILES
/dev/*flop*, /usr/include/sys/fdio.h
.SH "SEE ALSO"
fdc(1), far(1), bcp(N)