4.3BSD - /usr/man/cat4/rx.0

RX(4)                                                                    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 rx 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.  This mapping is always used by the block device.

       I/O requests must start on a sector boundary, involve an integral  num‐
       ber 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, 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  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.

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.

       [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 (i.e., calling close(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  dis‐
       played.

       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 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.


4.2 Berkeley Distribution        May 15, 1985                            RX(4)