Dual-system installation and startup principles

Source: Internet
Author: User

Let's talk about MBR (primary Boot Sector) and System Boot Sector:

The primary Boot Sector is located at the first of the hard disk and is responsible for searching the partitions that can be started by the hard disk. for DOS, it is generated by Fdisk, and the system Boot Sector is located at the first of each partition, this command is used to guide the corresponding operating system of the partition. It is the responsibility of the sys command.

Next, let's talk about the system startup:

Generally, Win98 is started by five files: io. sys, msdos. sys, command.com, autoexec. bat, and config. sys.

Win2000 and WinXP are started by Ntldr and Ntdetect files.

Win98 and Win2000/WinXP systems are complicated to start. It is started by OS Loaer. You can choose which system to start. If you choose to start Win2000/WinXP, the Ntldr and Ntdetect files are mounted to Win2000/WinXP. If you choose to start Win98, Bootsect is mounted. dos file, Bootsect. the dos file is actually an image of the Win98 Boot Sector.

By the way, both Win2000 and WinXP have two files Ntldr and Ntdetect, but they are different. If these two files are missing in your two systems, you can copy data from the I386 directory of the Win2000 or WinXP installation disk. If it is Win2000, you can use Win2000 or WinXP. If it is WinXP, you must use the WinXP disc. The two files in Win2000 cannot guide WinXP, this is particularly evident in the installation of multiple systems, including Win2000 and WinXP. For example, after you reinstall Win2000, you still cannot start WinXP, the reason is that you use the Ntldr and Ntdetec files of Win2000 to overwrite the Ntldr and Ntdetec files of WinXP. So be sure to pay attention to it!

Again, the Windows Multi-OS boot management tool: OS Loader. Every multi-OS boot management tool is different. For example, BootMagic and System Commander are resident in MBR, while OS Loader

It is resident in the System Boot Sector, while Linux's multi-system Boot Tool LILO or GRUB can be located either in MBR or in the System Boot Sector.

The above are some theoretical knowledge. Now that we have made it clear, we will go to the theoretical analysis stage to see why we cannot start Windows 98 After formatting the C drive:

In fact, the reason is very simple. After you reinstall Win98 on the drive C, four files are missing from the drive C, namely Ntldr, Ntdetec, and Bootsect. dos and boot. ini (configuration file for multi-system startup ). However, you only need to back up these four files before reinstalling them, and copy them back after reinstalling them. It is also impossible to achieve dual-start! The reason is that the system Boot Sector of your drive C has been overwritten by Win98: it changes the System Boot Sector previously controlled by OS Loader to the System Boot Sector of Win98, therefore, even if you copy the four files back, because the boot sector is still not restored to the Dual Boot Mode, you still cannot implement Dual Boot.

After knowing the cause, we can solve the problem with ideas and goals. That is to find a way to restore the system Boot Sector. There are several methods,

Method 1:

You can back up the System Boot Sector before reinstalling Win98. The DEBUG command is required!

The backup command is:

A:> debug

-L 100 2 0 1

-Na: OSLoader. REC

-Rcx

CX: 0000

200

-Rbx

X: 0000

: 0

-W

-Q

OSLoader generated on the floppy disk. the REC file is the backup of the Boot Sector of the OS Loader. If Bootsect is accidentally deleted. the dos file can be generated in a similar way. You only need to change the name of the file stored in the third row to Bootsect. dos.

You only need to re-write the OSLoader. REC file generated above, such as the hard drive boot sector, to restore the OS Loader boot function. Command:

A:> debug

-Na: Bootsect. dos

-L

-W100 2 0 1

-Q

After the OS Lode menu is fixed, if the C disk lacks Bootsect. dos file, which can be the Bootsect generated above. copy dos Files to drive C (Note: Bootsect generated on different machines. dos files are not generic ).

Method 2:

Use the fault console of Win2000 or WinXP to restore the Boot Sector:

Go to the fault console and enter:

Fixboot c:

Exit

Restart the computer.

Of course, both of these methods can be used to successfully recover the dual-boot function only when the above four files are backed up and recovered in advance. If these files are not backed up in advance, it will be more troublesome, A simple method is to use Win2000 or WinXP to install a disk, that is, a false installation method; the troublesome solution is to copy the Ntldr and Ntdetect files from the Win2000 and WinXP installation disks and generate the Bootsect file by running the DEBUG command. dos file, and then use the Win2000 or WinXP installation disk to enter the fault console, generate Boot. INI file (of course, if you are very familiar with the syntax of this file, you can also write a Boot file in Notepad under Win98 just like my master. INI file), and then repair the Boot Sector in the fault console!

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