


      DISC(7)                    (Bull-SPS9)                    DISC(7)



      NAME
           disc - disc device

      DESCRIPTION
           /dev/disc refers to the boot device.  The system
           automatically creates an entry called /dev/disc for the
           system boot device.

           disccu refers to a Bull-SPS9 disc device.  By convention, c
           is a controller number in the range 0..3, and u is a unit
           number on the controller in the range 0..3.


      DEVICE CODE
                                    block-type or  standard
           device type         major     minor     character-type file name

           boot disc      8    0    block          /dev/disc
           (system makes this)

           Disc device         8    U    block          /dev/discU
           (mknod(1) makes this)

           The minor number U is derived from a combination of the
           binary bits that represent the controller number and the
           unit number.  It is calculated by:

                                    (binary
           controller*    unit device-name    minor)    minor
                0    0    /dev/disc00    00-00     0
                0    1    /dev/disc01    00-01     1
                0    2    /dev/disc02    00-10     2
                0    3    /dev/disc03    00-11     3
                1    0    /dev/disc10    01-00     4
                1    1    /dev/disc11    01-01     5
                1    2    /dev/disc12    01-10     6
                1    3    /dev/disc13    01-11     7

           By convention, controller 0 is the device with "2" encoded
           on its address DIP-switches.

           The boot disc can be determined by checking the major and
           minor numbers of /dev/disc.


      FILES
           /dev/disc

           /dev/disc00 /dev/disc01 /dev/disc02 /dev/disc03

           /dev/disc10 /dev/disc11 /dev/disc12 /dev/disc13




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