Each DOS partition (also called a DOS volume) has its own volume boot sector.
This is distinct from the master boot sector (or record) that controls the entire
disk, but is similar in concept. Each volume boot sector contains the following:
- Disk Parameter Block: Also sometimes called the media parameter block,
this is a data table that contains specific information about the volume, such as its
specifications (size, number of sectors it contains, etc.), label name, etc.
- Volume Boot Code: This is code that is specific to the operating system that is
using this volume and is used to start the load of the operating system. This code is
called by the master boot code that is stored in the master boot record, but only for the
primary partition that is set as active. For other partitions, this code sits unused.
The volume boot sector is created when you do a high-level
format of a hard disk partition. The boot sector's code is executed directly when the
disk is booted, making it a favorite target for
virus writers.
Next: Active Partitions and Boot Managers
