Extended Boot Sector

Offset Size Description Comments
0 (0x00) 2BytesPerSectorShift - 4 ExtendedBootCode
2BytesPerSectorShift - 4 4 ExtendedBootSignature 0xAA550000

Whole sector is used for boot code except last 4 bytes used for signature in each sector. If Extended Boot Sector is not used, it should be filled with 0x00. Extended signature must be preserved.