INT 25 - DOS 3.31+ - ABSOLUTE DISK READ (>32M hard-disk partition)
        CX = FFFFh
        AL = drive number (0=A, 1=B, etc)
        DS:BX -> disk read packet (see below)
Return: same as above
Notes:  partition is potentially >32M (and requires this form of the call) if
          bit 1 of device attribute word in device driver is set
        original flags are left on stack, and must be removed by caller
        this call bypasses the DOS filesystem
SeeAlso: INT 13/AH=02h,INT 25,INT 26/CX=FFFFh

Format of disk read packet:
Offset  Size    Description
 00h    DWORD   sector number
 04h    WORD    number of sectors to read
 06h    DWORD   transfer address

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