Due to the size (64 bytes) of the MPT, a maximum of four partitions (16 bytes each) may be defined on a hard drive. However, additional partitions can be set up by defining one of the physical partitions as an extended partition and then defining additional logical partitions within that extended partition.
Master Partition Table Structure and Location
The master boot record includes 446 bytes of code, followed by the partition table with 64 bytes, and the remaining two bytes are reserved for the disk signature. Here are the specific duties of each 16 bytes of a master partition table: However, the partition table always keeps track of one partition that serves as the “Active” one that gets booted to if no other options are chosen. The partition type section of the partition table refers to the file system on that partition, where the 06 or 0E partition ID means FAT, 0B or 0C means FAT32, and 07 means NTFS or OS/2 HPFS. With a partition that’s 512 bytes for every sector, you need to multiply the total number of sectors by 512 to get the number of bytes of the total partition. That number can then be divided by 1,024 to get the number into kilobytes, and then again for megabytes, and again for gigabytes, if needed. After the first partition table, which is offset 1BE of the MBR, the other partition tables for the second, third, and fourth primary partition, are at 1CE, 1DE, and 1EE:
