INT 13H 16H: Detect Media Change

 Expects: AH    16H
          DL    diskette drive number: 00H thru 03H
 Returns: AH    00H = diskette change line not active
                01H = invalid drive number
                06H = either change line is not supported or
                      disk change line is active (media was swapped)
                80H = diskette drive not ready or not installed
                else= BIOS disk error code if CF is set to CY
    Info: This determines whether the door of a drive has been opened since
          the last time the change-line was cleared (it is cleared by all
          successful disk accesses).

          When change-line is active, it does not necessarily mean a new
          diskette is in place -- only that the drive door has been opened
          at some point.

   Notes: ■ Use INT 13H 15H to see if a drive supports change-line

See Also: INT 13H: BIOS Disk I/O
          BIOS Data Area
          ROM-BIOS Functions