CHKDSK Reports "Probable Non-DOS Disk"

MORE INFORMATION

• The disk was not formatted with the MS-DOS FORMAT command or was partitioned using a nonstandard partitioning scheme. The CHKDSK command should be used only on MS-DOS disks. Confirm that the disk or drive is an MS-DOS disk and that it is formatted.
  
  Some disks not formatted with the MS-DOS FORMAT command may cause the CHKDSK command to display this message; however, the CHKDSK process may still function properly. If you have a nonstandard partitioning scheme, make sure the correct device drivers are loaded.
• The media descriptor byte in one or both of the file allocation tables (FATs) for the drive producing the error message is incorrect or corrupted.
  
  If the drive has been partitioned and formatted with MS-DOS, you can use a disk editor (such a Norton DiskEdit) to edit the FAT. The FAT should be viewed as hexidecimal. The first byte in the FAT for a hard (fixed) disk should be "F8" (without the quotation marks). The following is an example of the first three lines of the FAT and the location of the media descriptor byte:

        00000000:  F8 FF FF FF 03 00 04 00 - 05 00 06 00 07 00 08 00
        00000010:  09 00 0A 00 0B 00 0C 00 - 0D 00 0E 00 0F 00 10 00
        00000020:  11 00 12 00 13 00 14 00 - 15 00 FF FF 17 00 18 00
  						

  WARNING: The above text is an example. You should NOT use a disk editor to change your FAT to match the above text.
  
  The media descriptor byte is the first two digits after the colon (:) in the first line, in this example. "F8." This is the correct setting for all MS-DOS formatted fixed disks (hard disk drives). Below is an abridged list of valid entries for the media descriptor byte and the media type the descriptor denotes:

        F8     Fixed disk
        F0     3.5-inch, 2-sided, 18-sector
        F9     3.5-inch, 2-sided, 9-sector
        F9     5.25-inch, 2-sided, 15-sector
        FC     5.25-inch, 1-sided, 9-sector
        FD     5.25-inch, 2-sided, 9-sector
        FE     5.25-inch, 1-sided, 8-sector
        FF     5.25-inch, 2-sided, 8-sector
        FE     8-inch, 1-sided, single-density
        FD     8-inch, 2-sided, single-density
        FE     8-inch, 2-sided, double-density
        FD     8-inch, 2-sided, double-density