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  In the PC/AT and PS/2 ROM BIOS, service 17H (decimal 23) describes the
  type of diskette in use in a specified drive. Call this service with a
  drive ID in register DL and a diskette-type ID in AL. (See Figure 10-6.)
  The ROM BIOS resets the diskette change status if it was previously set.
  It then records the diskette type in an internal status variable that can
  be referenced by other ROM BIOS services.

  Value                    Meaning
  --------------------------------------------------------------------------
  AL = 01H                 320/360 KB diskette in 360 KB drive
  AL = 02H                 360 KB diskette in 1.2 MB drive
  AL = 03H                 1.2 MB diskette in 1.2 MB drive
  AL = 04H                 720 KB diskette in 720 KB drive (PC/AT or PS/2)
                           or 720 KB or 1.44 MB diskette in 1.44 MB drive
                           (PS/2)
  --------------------------------------------------------------------------

  Figure 10-6.  Diskette-type ID values for diskette service 17H.