Basic knowledge of Hard Disk (MBR disk) Partitioning + Windows Startup Principle

We often see the following statements in Hard Disk Partitions: System partitions, startup partitions, active partitions, primary partitions, extended partitions, logical partitions, MBR, pbr, DPT, and primary boot sectors. In particular, when I see a lot of misleading information, I will be confused. Now I try to clarify the relationship between several people in the most concise language. If any error occurs, please leave it blank. First, each independent hard disk has only one primary Boot Sector MBR (512 bytes in total), recording the hard disk partition information. The Main Boot Sector includes Boot Loader (Main Boot Program, 446 bytes), DPT (Hard Disk Partition Table, 64 bytes), and Mn (magic number, 2 bytes ). This sector has nothing to do with whether it has been partitioned, it has nothing to do with the installed operating system, and the hard disk exists. PBR is a Partition Boot Record, which is available in each partition. Next, let's talk about the basic meaning of each partition. As we have mentioned above, DPT is a partition table, with a total of 64 bytes. Each partition parameter occupies 16 bytes. A simple division can be seen: A hard disk can be divided into up to four logical disks (independent from each other ). We can see that there may be many hard disk partitions. Why? This is the reason for introducing Extended partitions. The four logical disks independent from each other can be all primary partitions, that is, a maximum of four primary partitions can be divided. If there are only three primary partitions, the remaining Logical Disk is set to an extended partition, and the extended partition includes many interconnected logical partitions (not as independent as the primary partition ). In a word, Hard Disk Partitions include primary partitions + extended partitions. Extended partition = add multiple logical partitions. Again, the relationship between the three partitions: system partition, start partition, and active partition. The system partition and startup partition names seem to be reversed. The system partition contains the "Startup File" (ntldr, bootmgr, etc.), and the boot partition contains system files (such as Windows folders ). Each time the computer starts, there must be only one active partition, and the "Startup File" in the active partition is loaded. Therefore, the active partition is the system partition. Active partitions must also be primary partitions.

Speaking of this, the concept of "partition" is clarified. The following describes the system startup principle: 1. windows XP system boot: boot self-check-read MBR code into memory, management to the MBR-MBR read Partition Table DPT--DPT read active partitions in the hard disk (system control to the partition PBR ). So far, it has nothing to do with the installed system. As mentioned earlier, the active partition is the system partition, and the system partition contains the "Startup File" (ntldr)-then read the boot in the same directory. INI file (System Startup menu management File) -- enter WindowsXP system. 2. Windows 7 system boot: boot self-check-read MBR code into the memory, management to the MBR-MBR read Partition Table DPT--DPT read the active partition in the hard disk (system control to the partition PBR ). Restart -- enter the Windows 7 system. 3. Windows XP and Windows 7 dual system boot: boot self-check-read MBR code into the memory, management to the MBR-MBR read Partition Table DPT--DPT read the active partition in the hard disk (control of the system to the partition PBR ). So far, it has nothing to do with the installed system. As mentioned earlier, the active partition is the system partition, and the system partition contains the "boot file" (bootmgr) -- read \ Boot \ BCD and boot in the same directory. INI file-list the Startup Menu: If you select Windows 7 to be taken over by winload.exe, if you select Windows XP, ntldr will take over. Think about one question: why can I only Access Windows XP after I have installed Windows XP on Windows 7? A: PBR will be updated during system installation. in Windows XP, PBR is modified to be suitable for Windows XP, so you cannot enter Windows 7.