Such file-system-specific code would be too large to fit in thesingle 512 sectorInstead a specific diskaddress for the next 'chunk' is stored within the PPR.As mentioned above, the code in the PBR isspecific to the OS being loaded:For Windows the PBR loads an additional 16 sectors from the beginningof the partition.
In general, the job of the code in thePBR is to load a slightly larger 'next-step' program.The code in the PBR can't read afile system's directory structure to locate this next piece of code toload. Whereas the MBR code isoperating-system independent, the code in the PBR is supplied by andworks with a particular OS. The MBR (or the GRUB chainloader) loads the PBR intomemory and transfers control to it.
It is also sometimes referred to as the Volume Boot Record(VBR). Partition Boot Record (PBR) Partition Boot Record (PBR)The partition boot record is the first block of any bootablepartition.
