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(fdutils.info)Device numbers

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Device numbers
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   The floppy device nodes are usually made using the `MAKEFLOPPIES'
shell script (Note: makefloppies).

   The major device number for the floppy drives is 2.  The minor device
number contains describes which drive it represents, and may in addition
describe the kind of media which is currently in the drive.

   There are two kind of floppy devices:
   * Variable geometry device nodes. Their minor number doesn't depend
     on the media in the drive, and is calculated as follows:
          MINOR_DEVICE = 128 * FDC_NR + UNIT_NR

   * Fixed geometry device nodes. Their minor number not only depends
     on the drive which they represent, but also the type of media
     currently in the drive.  It is computed as follows:

          MINOR_DEVICE = 128 * FDC_NR + UNIT_NR + 4 * FORMAT_NR


   In this formula, FDC_NR is the number of the floppy disk controller
(0 or 1, usually 0), and UNIT_NR is the Unit number (0 to 3, 0 for Dos
drive `A:', and 1 for Dos drive `B:').  FORMAT_NR is only meaningful
for the fixed format devices. It describes the disk geometry that is
used.  It is an index into the _geometry list_ Note: geometry list.
Using all available controller numbers and all available drive numbers,
you may thus connect up to 8 floppy drives to a single Linux box.

Variable format devices

Fixed format devices

geometry list

Adding new formats