DBR start offset 0x5A data for the operating system boot code. This is offset by the start of the jump instruction 0x00 points. At offset 0x00 ~ 0x02 jump instructions listed in Figure 8 "EB 58 90" clearly indicate the OS boot code offset. jump 58H with the desired amount of displacement of a jump instruction, which starts at 0x5A. This section of the boot instructions and different ways on different operating systems, its content is different. Say win98, win2000 fat build on the basic partition, DBR winxp used only occupy the first primary partition sector 0 on most data. They mentioned, for fat32, generally 32 reserved sectors, only the first primary partition 0 sector is useful. In fact, in order to build an operating system FAT32 if it is win98, the system will use the first primary partition 0 sector and the second sector os boot code storage; built to FAT32 if the operating system is win2000 or winxp, the system uses the basic partition 0 of sectors and 0xC sector (win2000 or winxp, the location of its first 0xC 0xAB 0th sector offset noted) os boot code storage. So, in the fat32 partition format, if the contents of DBR and the lack of a proper sector 2 sector (win98 system) or 0xC sector (win2000 or winxp system), the system also will not start. If you manually set your own NTLDR dual system, you must know that. 
     DBR DBR valid flag last two bytes to store the value 0x55AA sector in general, and for other values, the system will not run DBR related instructions. Several other sectors involved in the above-mentioned guide os also need to 0x55AA end flag is legal.

FAT16 DBR: 
     the DBR generally true meaning of FAT32, FAT12 and FAT16 for its basic meaning is similar, but the meaning and parameters related to offset a small difference, and the difference between FAT format to reason, we will discuss later, not much here says FAT12 and FAT16. I will list the sector parameter significance of FAT16. Interested friends to look at yourself, and FAT32 or less the same.