Partition Magic - Partition Manager Software

Extend partition with one step
Resize/Move partition without data loss.
Create, delete and format partion with simple steps. Copy partition and disk to transfer data with ease. Support disk and partition size larger than 2 TB. Keep your data safe even in case of power outages or hardware failure.

Understanding How a Computer Boots

The way a computer boots from a hard disk depends on the way the hard disk is partitioned and on the operating system being booted.

The Basic Boot Process
When you turn on the power to your computer, the central processing unit (CPU) takes control. The CPU immediately executes the instructions built into the computer's ROM BIOS, a program that contains the startup procedures. The last part of the BIOS instructions contains the boot routine. This routine is programmed to read the master boot record (MBR) from the first sector of the first physical hard disk.

The MBR contains a master boot program and a partition table that describes all of the hard disk's partitions. The BIOS boot routine executes the master boot program, which then continues the boot process. The master boot program looks at the partition table to see which primary partition is active. If there is only one primary partition, that partition's OS is loaded and booted into operation.
If the hard disk has more than one primary partition, each bootable partition has its own boot record stored in its first sector. This boot record holds a boot program designed specifically to start that partition's installed OS. This OS-specific boot record is usually written to the partition when the partition is logically formatted, but can also be added later with an OS-specific utility (for example, the DOS SYS utility, and so on).
After identifying the active partition, the master boot program starts that partition's boot program. In turn, the boot program loads the necessary OS files and starts the OS.

Operating System-Specific Boot Information
Most operating systems, including DOS, Windows 3.x, Windows 95/98, and Windows NT, rely on the active primary partition when they boot from a hard disk. However, different operating systems rely on the active primary partition in different ways.

1. DOS, Windows 3.x, and Windows 95/98 must boot from an active primary partition on the first hard disk drive.
2. Windows NT can boot from a logical partition, but the Windows NT boot program must be in the active primary partition on the first hard disk.