Table 5.2 Data structure for DOS partition entries. Byte Range Description Essential 0-0 Bootable Flag No 1-3 Starting CHS Address Yes 44 Partition Type (see Table 5.3) No 5-7 Ending CHS Address Yes 8-11 Starting LBA Address Yes 12-15 Size in Sectors Yes The bootable flag is not always necessary. The standard boot code for a system with only one OS looks for an entry whose flag is set to 0x80. For example, if a system has Microsoft Windows on it and the disk is partitioned into two partitions, the partition with the operating system on it (C:\windows, for example) will have the bootable flag set. On the other hand, if the boot code prompts the user to choose which partition to boot from, the bootable flag is not necessary. Although, some boot programs will set the bootable flag after the user chooses to boot that partition. The starting and ending CHS addresses have an 8-bit head value, a 6-bit sector value, and a 10-bit cylinder value. In theory, either the CHS addresses or the LBA addresses need to be set for each partition, but not both. It is up to the OS and the code that is used to boot the system to determine which values need to be set. For example, Windows 98 and ME use the CHS addresses for partitions in the first 7.8GB of the disk, but Windows 2000 and beyond always ignore the CHS addresses [Microsoft 2003]. Some partitioning tools set both when possible for backward compatibility. The usage of these fields is application-dependent. The partition type field identifies the file system type that should be in the partition. A list of common partition types is given in Table 5.3. A more detailed list of partition types can be found in Partition types [Brouwer 2004]. Table 5.3 Some of the type values for DOS partitions. Туре Description 0x00 Empty 0x01 FAT12, CHS 0x04 FAT16, 16-32 MB, CHS Table 5.3 Some of the type values for DOS partitions (continued). Type 0x05 Description Microsoft Extended, CHS 0x06 FAT16, 32 MB-2GB, CHS NTFS FAT32, CHS FAT32, LBA FAT16, 32 MB-2GB, LBA Microsoft Extended, LBA Hidden FAT12, CHS Hidden FAT16, 16-32 MB, CHS Hidden FAT16, 32 MB-2GB, CHS Hidden FAT32, CHS Hidden FAT32, LBA 0x07 0x0b 0x0c 0x0e OxOf 0x11 0x14 0x16 Oxlb Oxlc Oxle 0x42 0x82 0x82 0x83 0x84 0x85 Linux Extended 0x86 NTFS Volume Set 0x87 NTFS Volume Set Oxa0 Hibernation Hidden FAT16, 32 MB-2GB, LBA Microsoft MBR. Dynamic Disk Solaris x86 Linux Swap Linux Hibernation Oxal Hibernation Oxa5 FreeBSD Охаб OpenBSD 90

Table 5.2 Data structure for DOS partition entries. Byte Range Description Essential 0-0 Bootable Flag No 1-3 Starting CHS Address Yes 44 Partition Type (see Table 5.3) No 5-7 Ending CHS Address Yes 8-11 Starting LBA Address Yes 12-15 Size in Sectors Yes The bootable flag is not always necessary. The standard boot code for a system with only one OS looks for an entry whose flag is set to 0x80. For example, if a system has Microsoft Windows on it and the disk is partitioned into two partitions, the partition with the operating system on it (C:\windows, for example) will have the bootable flag set. On the other hand, if the boot code prompts the user to choose which partition to boot from, the bootable flag is not necessary. Although, some boot programs will set the bootable flag after the user chooses to boot that partition. The starting and ending CHS addresses have an 8-bit head value, a 6-bit sector value, and a 10-bit cylinder value. In theory, either the CHS addresses or the LBA addresses need to be set for each partition, but not both. It is up to the OS and the code that is used to boot the system to determine which values need to be set. For example, Windows 98 and ME use the CHS addresses for partitions in the first 7.8GB of the disk, but Windows 2000 and beyond always ignore the CHS addresses [Microsoft 2003]. Some partitioning tools set both when possible for backward compatibility. The usage of these fields is application-dependent. The partition type field identifies the file system type that should be in the partition. A list of common partition types is given in Table 5.3. A more detailed list of partition types can be found in Partition types [Brouwer 2004]. Table 5.3 Some of the type values for DOS partitions. Туре Description 0x00 Empty 0x01 FAT12, CHS 0x04 FAT16, 16-32 MB, CHS Table 5.3 Some of the type values for DOS partitions (continued). Type 0x05 Description Microsoft Extended, CHS 0x06 FAT16, 32 MB-2GB, CHS NTFS FAT32, CHS FAT32, LBA FAT16, 32 MB-2GB, LBA Microsoft Extended, LBA Hidden FAT12, CHS Hidden FAT16, 16-32 MB, CHS Hidden FAT16, 32 MB-2GB, CHS Hidden FAT32, CHS Hidden FAT32, LBA 0x07 0x0b 0x0c 0x0e OxOf 0x11 0x14 0x16 Oxlb Oxlc Oxle 0x42 0x82 0x82 0x83 0x84 0x85 Linux Extended 0x86 NTFS Volume Set 0x87 NTFS Volume Set Oxa0 Hibernation Hidden FAT16, 32 MB-2GB, LBA Microsoft MBR. Dynamic Disk Solaris x86 Linux Swap Linux Hibernation Oxal Hibernation Oxa5 FreeBSD Охаб OpenBSD 90