Click above to get retro games delivered to your door ever month!

  An extended FCB has two additional fields not found in a normal FCB:

  .  The first field of an extended FCB is a flag byte whose contents must
     be FFH. DOS distinguishes between normal and extended FCBs by examining
     this byte. (In a normal FCB, the first field is the disk-drive
     specifier, which should never be FFH.)

  .  Offset 06H in an extended FCB is a 1-byte field that consists of an
     attribute byte whose bits signify file, volume label, and subdirectory
     attributes. This byte's format is identical to the attribute byte in a
     directory entry. (See Chapter 5.)

  --------------------------------------------------------------------------
  NOTE:
    One rare situation in which you would use FCB-based functions instead of
    handle-based functions is when you work with a disk's volume label. DOS
    versions 2.0 and later do not provide any special services for
    manipulating a volume label. You must use function 16H with an extended
    FCB to create a volume label, function 17H to rename it, and function
    13H to rename it.
  --------------------------------------------------------------------------