现在许多网友在使用WinNT/2K/XP等操作系统了。可是，当他们启动了WinNT/2K/XP后，发现许多DOS程序都无法在它上面运行了，而且也无法使用纯DOS了。这是怎么回事呢？
大家知道，WinNT/2K/XP中有个叫“命令提示符”的东东，表面看上去类似于Win3.x/9x中的MS-DOS窗口。然而，它们是完全不同的。Win3.x/9x是运行于MS-DOS下的大型保护模式的GUI界面增强程序，而WinNT/2K/XP则是基于OS/2、NT构件的独立操作系统，因此，它们之间有着本质的不同。真正的DOS是MS-DOS、PC-DOS等纯DOS，而WinNT/2K/XP中的“命令提示符”仅仅是个“WinNT系统控制台”，其中带有一部分“DOS虚拟机”的功能。既然是虚拟的，效果自然没有真正的好。因此，当这个“虚拟的DOS”无法正常运行DOS程序时，只有使用真正的DOS（例如MS-DOS 7.10）以运行它们。
由于WinNT/2K/XP不带有DOS，所以要想在安装了这些操作系统后又想用硬盘安装纯DOS系统的话，只能使用双启动。很多网友知道WinNT/2K/XP启动时往往会出现一个菜单，可以从中选择要启动的操作系统。然而，有时此菜单中并没有“DOS”这个选项，甚至启动时根本没有出现此启动菜单（如果在安装WinNT/2K/XP时选择保留原操作系统的话，WinNT/2K/XP的启动菜单中就会出现原来操作系统的选项）。那么该怎么办呢？以下介绍一下在安装了WinNT/2K/XP后再安装DOS的方法。
DOS的启动需要DOS系统的引导扇区和启动文件。DOS安装程序在安装时会自动重建DOS的引导扇区和启动文件，这样安装后就可以启动DOS了。然而，对于旧版本的DOS（如MS-DOS 6.x）而言，它们的安装程序会覆盖掉WinNT/2K/XP的引导信息，导致WinNT/2K/XP无法启动。用DOS自带的SYS等命令传输也会是这种情况。所以，为了使DOS和WinNT/2K/XP均能启动，应该用更好的方法，或者用能够自动做成DOS与WinNT/2K/XP双启动的DOS安装程序来自动完成。
MS-DOS 7.10是目前功能最强大实用，且兼容性最好的DOS。而且由于它全面支持大硬盘、大内存、长文件名（LFN）、FAT32分区、可能直接启动Win3.x/9x等等，所以非常实用。而且它的安装程序就全面支持与WinNT/2K/XP并存。“MS-DOS 7.10完整安装版”（可以在“DOS系统”中下载）在安装中可以让系统自动完成在WinNT/2K/XP下安装DOS完整版的操作，并自动实现DOS与WinNT/2K/XP的双启动。由于MS-DOS 7.10完整安装版非常强大实用，所以推荐大家使用。更详细信息可以在下面这篇文章中看到：
http://dos.qiee.com/newdos/dosart32.htm 链接已失效（管理员注）
不过，如果硬盘的主分区（通常是C盘）是NTFS格式的，那是不能直接安装DOS的，因为DOS不直接支持NTFS格式。这时可以用一些多启动管理器来实现，例如SPFDISK等。在用多启动盘管理器设置好系统分区后，直接安装MS-DOS 7.10即可实现与WinNT/2K/XP的共存。
另外，除安装DOS或用真实DOS启动软盘启动DOS外，还可以利用虚拟软盘镜像的方法来启动DOS，也就是从WinNT/2K/XP的开机菜单中直接启动虚拟的DOS启动软盘中的DOS，相当于从DOS启动软盘启动。可以通过用VFloppy、GRUB for NTLDR等软件来实现，具体可以在本论坛的相关帖子中看到和下载。不过请注意，用虚拟软盘或真实软盘来启动到DOS都不是安装DOS，如果要真正安装DOS的话则需用DOS安装程序来自动安装。
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除上面所提到安装DOS完整版等方法外，WinNT/2K/XP下增加纯DOS还有其它方法，有些方法需要手工修改系统配置，或手工用一系列命令行操作等方式来实现，例如chujiafu在下面的帖子中向大家分享的方法就是一例，适合于对电脑有一定水平的人，对这些人来说此方法可能会更快捷。不过要注意的是这样增加的DOS只是最简易的能启动的精简DOS系统，而非DOS完整版，如果需要的话还需进行进一步的系统配置等。详见此帖：
http://www.cn-dos.net/forum/viewthread.php?tid=16762
Now many netizens are using operating systems such as WinNT/2K/XP. However, when they start WinNT/2K/XP, they find that many DOS programs cannot run on it, and pure DOS cannot be used either. What's the matter?
Everyone knows that there is something called "Command Prompt" in WinNT/2K/XP, which looks similar to the MS-DOS window in Win3.x/9x on the surface. However, they are completely different. Win3.x/9x is a large protected-mode GUI interface enhancement program running under MS-DOS, while WinNT/2K/XP is an independent operating system based on OS/2 and NT components. Therefore, there are essential differences between them. The real DOS is pure DOS such as MS-DOS and PC-DOS, while the "Command Prompt" in WinNT/2K/XP is just a "WinNT system console" with part of the functions of "DOS virtual machine". Since it is virtual, the effect is naturally not as good as the real one. Therefore, when this "virtual DOS" cannot run DOS programs normally, only the real DOS (such as MS-DOS 7.10) can be used to run them.
Since WinNT/2K/XP does not come with DOS, if you want to install pure DOS on the hard disk after installing these operating systems, you can only use dual-booting. Many netizens know that when WinNT/2K/XP starts, a menu often appears from which you can select the operating system to start. However, sometimes there is no "DOS" option in this menu, and even the boot menu does not appear at all (if you choose to retain the original operating system when installing WinNT/2K/XP, the boot menu of WinNT/2K/XP will have the option of the original operating system). So what should be done? The following introduces the method of installing DOS after installing WinNT/2K/XP.
The startup of DOS requires the boot sector and startup files of the DOS system. The DOS installation program will automatically rebuild the boot sector and startup files of DOS during installation, so that DOS can be started after installation. However, for older versions of DOS (such as MS-DOS 6.x), their installation programs will overwrite the boot information of WinNT/2K/XP, causing WinNT/2K/XP to fail to start. The same situation will occur when using the SYS and other commands brought by DOS for transmission. Therefore, in order to make both DOS and WinNT/2K/XP startable, a better method should be used, or a DOS installation program that can automatically make a dual-boot of DOS and WinNT/2K/XP should be used to complete it automatically.
MS-DOS 7.10 is currently the most powerful, practical, and most compatible DOS. Moreover, since it fully supports large hard disks, large memory, long file names (LFN), FAT32 partitions, and may directly start Win3.x/9x, etc., it is very practical. And its installation program fully supports coexistence with WinNT/2K/XP. The "MS-DOS 7.10 Complete Installation Edition" (can be downloaded in "DOS System") can let the system automatically complete the operation of installing the full version of DOS under WinNT/2K/XP during installation, and automatically realize the dual-boot of DOS and WinNT/2K/XP. Since the MS-DOS 7.10 Complete Installation Edition is very powerful and practical, it is recommended for everyone to use. More detailed information can be seen in the following article:
http://dos.qiee.com/newdos/dosart32.htm The link is invalid (note from administrator)
However, if the primary partition (usually drive C) of the hard disk is in NTFS format, DOS cannot be installed directly because DOS does not directly support the NTFS format. At this time, some multi-boot managers can be used, such as SPFDISK, etc. After setting the system partition with the multi-boot disk manager, directly installing MS-DOS 7.10 can realize coexistence with WinNT/2K/XP.
In addition to installing DOS or starting DOS with a real DOS boot floppy, the method of starting DOS by using a virtual floppy disk image can also be used, that is, directly start the DOS in the virtual DOS boot floppy from the boot menu of WinNT/2K/XP, which is equivalent to starting from the DOS boot floppy. It can be realized by using software such as VFloppy, GRUB for NTLDR, etc., and the specific content can be seen and downloaded in the relevant posts of this forum. However, please note that starting to DOS with a virtual floppy or a real floppy is not installing DOS. If you want to really install DOS, you need to use the DOS installation program to install it automatically.
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In addition to the methods such as installing the full version of DOS mentioned above, there are other methods to add pure DOS under WinNT/2K/XP. Some methods need to manually modify the system configuration or manually use a series of command line operations, etc. For example, the method shared by chujiafu in the following post is an example, which is suitable for people with a certain level of computer. For these people, this method may be faster. However, it should be noted that the DOS added in this way is only the simplest startable streamlined DOS system, not the full version of DOS. If needed, further system configuration, etc. are required. For details, see this post:
http://www.cn-dos.net/forum/viewthread.php?tid=16762