urx(4) Unsupported urx(4)Nameurx - DEC RX02 floppy disk interface
Syntax
controller fx0 at uba0 csr 0177170 vector rxintr
disk rx0 at fx0 drive 0
disk rx1 at fx0 slave 1
Description
The device provides access to a DEC RX02 floppy disk unit with M8256
interface module (RX211 configuration). The RX02 uses 8-inch, single-
sided, soft-sectored floppy disks (with pre-formatted industry-standard
headers) in either single or double density.
Floppy disks handled by the RX02 contain 77 tracks, each with 26 sec‐
tors (for a total of 2,002 sectors). The sector size is 128 bytes for
single density, 256 bytes for double density. Single density disks are
compatible with the RX01 floppy disk unit and with IBM 3740 Series
Diskette 1 systems.
In addition to normal (`block' and `raw') i/o, the driver supports for‐
matting of disks for either density and the ability to invoke a 2 for 1
interleaved sector mapping compatible with the DEC operating system
RT-11.
The minor device number is interpreted as follows:
Bit Description
0 Sector interleaving (1 disables interleaving)
1 Logical sector 1 is on track 1 (0 no, 1 yes)
2 Not used, reserved
Other Drive number
The two drives in a single RX02 unit are treated as two disks attached
to a single controller. Thus, if there are two RX02's on a system, the
drives on the first RX02 are ``rx0'' and ``rx1'', while the drives on
the second are ``rx2'' and ``rx3''.
When the device is opened, the density of the disk currently in the
drive is automatically determined. If there is no floppy in the device,
open will fail.
The interleaving parameters are represented in raw device names by the
letters `a' through `d'. Thus, unit 0, drive 0 is called by one of the
following names:
Mapping Device name Starting track
interleaved /dev/rrx0a 0
direct /dev/rrx0b 0
interleaved /dev/rrx0c 1
direct /dev/rrx0d 1
The mapping used on the `c' device is compatible with the DEC operating
system RT-11. The `b' device accesses the sectors of the disk in
strictly sequential order. The `a' device is the most efficient for
disk-to-disk copying.
The I/O requests must start on a sector boundary, involve an integral
number of complete sectors, and not go off the end of the disk.
Notes
Even though the storage capacity on a floppy disk is quite small, it is
possible to make filesystems on double density disks. For example, the
command
% mkfs /dev/rx0 1001 13 1 4096 512 32 0 4
makes a file system on the double density disk in rx0 with 436 kbytes
available for file storage. Using tar(1) gives a more efficient uti‐
lization of the available space for file storage. Single density
diskettes do not provide sufficient storage capacity to hold file sys‐
tems.
A number of ioctl(2) calls apply to the rx devices, and have the form
#include <vaxuba/rxreg.h>
ioctl(fildes, code, arg)
int *arg;
The applicable codes are:
RXIOC_FORMAT Format the diskette. The density to use is specified
by the arg argument, 0 gives single density while
non-zero gives double density.
RXIOC_GETDENS Return the density of the diskette (0 or !=0 as
above).
RXIOC_WDDMK On the next write, include a deleted data address
mark in the header of the first sector.
RXIOC_RDDMK Return non-zero if the last sector read contained a
deleted data address mark in its header, otherwise
return 0.
Restrictions
A floppy may not be formatted if the header information on sector 1,
track 0 has been damaged. Hence, it is not possible to format com‐
pletely degaussed disks or disks with other formats than the two known
by the hardware.
If the drive subsystem is powered down when the machine is booted, the
controller won't interrupt.
Diagnostics
The following errors may be returned by the above ioctl calls:
[ENODEV] Drive not ready; usually because no disk is in the drive or
the drive door is open.
[ENXIO] Nonexistent drive (on open); offset is too large or not on
a sector boundary or byte count is not a multiple of the
sector size (on read or write); or bad (undefined) ioctl
code.
[EIO] A physical error other than ``not ready'', probably bad
media or unknown format.
[EBUSY] Drive has been opened for exclusive access.
[EBADF] No write access (on format), or wrong density; the latter
can only happen if the disk is changed without closing the
device, that is, calling close(2).
rx%d: hard error, trk %d psec %d cs=%b, db=%b, err=%x, %x, %x, %x.
An unrecoverable error was encountered. The track and physical sector
numbers, the device registers and the extended error status are dis‐
played.
rx%d: state %d (reset).
The driver entered a bogus state. This should not happen.
FilesSee Alsotar(1), arff(8v), mkfs(8), newfs(8), rxformat(8v)
VAX urx(4)
