1.1.1 Partition Table Contents
A partition table consists of four 16 Byte entries. Each entry contains the
following data:
- Bootable Partition Flag
- The bootable flag lets the DOS boot loader know that the partition can be
booted. MS DOS requires that only one partition be marked as bootable or
active. If more than one partition is marked active a message like
‘Invalid partition table’.
- Starting CHS
- The starting CHS1 tells where
the partition starts on the hard drive physically.
- System Indicator Byte
- The system indicator is a single byte that describes the file system that
resides on the partition. Each file system type has a file system ID. For
instance, a primary FAT 16 partition that is larger than 32 Mb would have a
file system ID of 06h. One major limitation of the system indicator byte is
that it is only 8 bits, which provides only 256 unique file system types.
Setting this byte in a partition table entry to a value that is unrecognized
by DOS would make DOS ignore that file system.
- Ending CHS
- The ending CHS tells where the partition ends on the hard drive physically.
- Relative Sector Offset
- The relative sector offset is the number of sectors before the partition on the
disk. It could also be described as the number of sectors between the starting
CHS and cylinder 0, head 0, sector 1.
- Sector Count
- The total number of sectors in the partition