4.3BSD-UWisc/man/cat4/rx.4
RX(4) UNIX Programmer's Manual RX(4)
NAME
rx - DEC RX02 floppy disk interface
SYNOPSIS
controller fx0 at uba0 csr 0177170 vector rxintr
disk rx0 at fx0 drive 0
disk rx1 at fx0 drive 1
DESCRIPTION
The _r_x 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 sectors (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 sys-
tems.
In addition to normal (`block' and `raw') i/o, the driver
supports formatting of disks for either density and the
ability to invoke a 2 for 1 interleaved sector mapping com-
patible 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
Printed 12/27/86 May 15, 1985 1
RX(4) UNIX Programmer's Manual RX(4)
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. This
mapping is always used by the block device.
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 _t_a_r(1) gives a
more efficient utilization of the available space for file
storage. Single density diskettes do not provide sufficient
storage capacity to hold file systems.
A number of _i_o_c_t_l(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 _a_r_g argument, zero gives
single density while non-zero gives double
density.
RXIOC_GETDENS Return the density of the diskette (zero
or non-zero as above).
RXIOC_WDDMK On the next write, include a _d_e_l_e_t_e_d _d_a_t_a
_a_d_d_r_e_s_s _m_a_r_k in the header of the first
sector.
RXIOC_RDDMK Return non-zero if the last sector read
contained a _d_e_l_e_t_e_d _d_a_t_a _a_d_d_r_e_s_s _m_a_r_k in
its header, otherwise return 0.
ERRORS
The following errors may be returned by the driver:
[ENODEV] Drive not ready; usually because no disk is in
the drive or the drive door is open.
Printed 12/27/86 May 15, 1985 2
RX(4) UNIX Programmer's Manual RX(4)
[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'', prob-
ably 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 _c_l_o_s_i_n_g the device (i.e., cal-
ling _c_l_o_s_e(2) ).
FILES
/dev/rx?
/dev/rrx?[a-d]
SEE ALSO
rxformat(8V), newfs(8), mkfs(8), tar(1), arff(8V)
DIAGNOSTICS
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 displayed.
rx%d: state %d (reset). The driver entered a bogus state.
This should not happen.
BUGS
A floppy may not be formatted if the header info on sector
1, track 0 has been damaged. Hence, it is not possible to
format completely degaussed disks or disks with other for-
mats than the two known by the hardware.
If the drive subsystem is powered down when the machine is
booted, the controller won't interrupt.
Printed 12/27/86 May 15, 1985 3