中国DOS联盟

A few days ago, I installed MS-DOS 7.10 in the first primary partition on the hard drive; then I activated the second primary partition and installed XP-SP2 using the XP CD. Without third-party software, dual-booting couldn't be achieved. Also, there was no dual-boot menu. Yesterday, I repartitioned; the first primary partition still had MS-DOS 7.10 installed. Then I booted into the DOS system and installed XP-SP2 at the command line. When XP-SP2 was installed, the system automatically appeared with a dual-boot menu and could boot MS-DOS normally. XP-SP2 was also installed in the second primary partition. What's the reason for this? :o

Heheh, when installing for the second time, no matter which partition on the hard drive (any visible partition) you install XP to, the system will automatically have a dual-boot menu. As for the reason, simply put, XP supports multi-system booting. More complicatedly: http://www.cn-dos.net/forum/viewthread.php?tid=18898&fpage=1; to go deeper: just lurk more.

I don't know how you operate! I install different systems on two different primary partitions with CDs respectively. Even if I follow the installation method from lower-level system to higher-level system, there won't be a multi-boot menu! Only when I install the higher-level system to another primary partition under the already installed lower-level system, will the multi-boot menu appear! At this time, the boot files of the higher-level system are all in the root directory of the system disk where the lower-level system is located, and the drive letter of the lower-level system disk is C.

Re the original poster:

The reason is very simple. For the first installation method you used, you must have activated different primary partitions before starting to install the system. In this way, the two systems use different boot sectors (the boot sectors of their respective primary partitions). To switch between these two systems, you can only do it by activating the corresponding partition. For the second installation method, the two systems share one primary partition's boot sector. That is to say, the original DOS boot sector is saved by XP as c:\bootsect.dos, and XP replaces the original DOS boot sector with its own boot sector. At the same time, it adds an item c:\="...." in its own startup menu, which is to load the DOS boot sector file bootsect.dos.

Haven't you noticed that the effects after starting with the two installation methods are different? In the first installation method, the C: drive changes. When starting DOS, the primary partition where DOS is located is C:, and when starting XP, the primary partition where XP is located becomes C:. In the second method, the C: drive remains unchanged, always the primary partition where DOS is located, and after XP starts, the partition it is on is no longer C:.

In fact, you can simply modify the first method to make XP also support booting another primary partition's DOS (save the boot sector of the DOS primary partition as a file, and then load it through XP's boot.ini). Of course, if you use a boot management software like grub4dos, it is easier to achieve.

Last edited by Climbing on 2007-6-6 at 01:40 PM ]