HPFS Large Disk Access

DosRead/Write in direct-access mode will normally fail if the partition is greater than four gigabytes in size. If you wish to write an HPFS editor or other tool, you will need to know the "secret password" that unlocks the big disks. After you use DosOpen to get a handle to that volume, use FSCTL FSC_SECTORIO (0x9014) and in the parameter list, put a pointer to 0xDEADFACE. Doing so will put the handle in "sector" mode. All offsets and sizes will refer to sectors instead of bytes, allowing you to address 64Gb.

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