Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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▀ The media ID byte has the following meanings:
  0F0H    3.5-inch double-sided, 18 sectors
          or "other"
  0F8H    fixed disk
  0F9H    5.25-inch double-sided, 15 sectors
          or 3.5-inch double-sided, 9 sectors
  0FCH    5.25-inch single-sided, 9 sectors
  0FDH    5.25-inch double-sided, 9 sectors
  0FEH    5.25-inch single-sided, 8 sectors
  0FFH    5.25-inch double-sided, 8 sectors
 
▀ To obtain information about disks other than the one in the default
  drive, use Int 21H Function 1CH or 36H.
 
▀ The address returned in DS:BX points only to a copy of the media ID
  byte from the disk's FAT; the memory above that address cannot be
  assumed to contain the FAT or any other useful information. If direct
  access to the FAT is required, use Int 25H to read it into memory.
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