


      BADBLOCKS(4)               (Bull-SPS9)               BADBLOCKS(4)



      NAME
           badblocks - media defect list for SMD disc in companion
           cabinet

      DESCRIPTION
           Badblocks is the only file on the "badblocks" floppy disc
           (or cartridge tape) shipped with each SMD disc.

           Winchester-type discs (including all Bull-SPS9 discs), come
           from the factory with a list of their own manufacturing
           defects. For the 60-Mb and 142-Mb discs in the Bull-SPS9
           cabinet, the bad block table is permanently encoded on the
           disc and printed on paper in a plastic pocket that stays
           with the unit.  For the others SMD disc unit in the
           companion cabinet, the bad block information is distributed
           on a separate floppy disc or cartridge tape.

           The badblocks file on the badblocks floppy disc (or
           cartridge tape) describes the cylinder, surface (or head),
           byte offset from the disc index mark, and length of each
           defect.

           On ROS 3.1 and subsequent releases, the defect list is kept
           in the following format:

                cyl-num  head-num byte-offset length

           example:

                 12  4  2359  16
                104  7 12304   3
                 66  5  3412   2


           In the sad event that the system must be rebuilt, the SMD
           badblocks floppy (or cartridge) must be available.



















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