controller fdc0 at atmem ? csr 0x1000 dmachan 2 irq 6 priority 2 disk fd0 at fdc0 drive 0 flags 0
controller fdc0 at obio ? csr 0x6e000000 priority 6 vector fdintr 0x5c disk fd0 at fdc0 drive 0 flags 0
Sun386i, Sun-3/80, and Desktop SPARCsystems only.
The fd driver provides an interface to floppy disks using the Intel 82072 disk controller on Sun386i, Sun-3/80 and Desktop SPARCsystems.
The minor device number in files that use the floppy interface encodes the unit number as well as the partition. The bits of the minor device number are defined as rrruuppp where r=reserved, u=unit, and p=partition. The unit number selects a particular floppy drive for the controller. The partition number picks one of eight partitions [a-h].
When the floppy is first opened the driver looks for a label in logical block 0 of the diskette. If a label is found, the geometry and partition information from the label will be used on each access thereafter. The driver first assumes high density characteristics when it tries to read the label. If the read fails it will try the read again using low density characteristics. If both attempts to read the label fail, the open will fail. Use the FNDELAY flag when opening an unformatted diskette as a signal to the driver that it should not attempt to access the diskette. If block 0 is read successfully, but a label is not found, the open will fail for the block interface. Using the raw interface, the open will succeed even if the diskette is unlabeled. Default geometry and partitioning are assumed if the diskette is unlabeled.
The default partitions are:
The fd driver supports both block and raw interfaces. The block files access the disk using the system's normal buffering mechanism and may be read and written without regard to physical disk records. There is also a ``raw'' interface that provides for direct transmission between the disk and the user's read or write buffer. A single read.2v or write.2v call usually results in one I/O operation; therefore raw I/O is considerably more efficient when many words are transmitted. The names of the raw files conventionally begin with an extra `r'.
1.44 MB Floppy Disk Drives:
720 K Floppy Disk Drives:
Note: the fd driver on Sun-3/80 and Desktop SPARCsystems auto-senses the density of the floppy.
Floppy diskettes have 18 sectors per track, and can cross a track (though not a cylinder) boundary without lossing data, so when using dd.1 to or from a diskette, you should specify bs=18k or multiples thereof.
Created by unroff & hp-tools. © by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97