struct _CM_DISK_GEOMETRY_DEVICE_DATA {
unsigned long BytesPerSector;/* 0x0 4 */
unsigned long NumberOfCylinders;/* 0x4 4 */
unsigned long SectorsPerTrack;/* 0x8 4 */
unsigned long NumberOfHeads;/* 0xc 4 */
};
/* computed from the NT 4.0 DDK headers */