China DOS Union

My machine already has 98 and 2000. Without damaging the original systems (without reinstalling 98 or 2000), is it possible to add DOS? How do I install it?
In 98, are io.sys, msdos.sys, command, autoexec.bat, and config.sys running? If we want to change them, what should we do?
In 98 there are several ways to get to DOS, for example shutting down and going back into DOS, or going to DOS from the Start menu.
And when window98 starts, pressing F8 to enter DOS. What is the difference between these situations...?
Hehe, a newbie asks a lot, and asks all kinds of things.
If you want to learn DOS, you have to first understand these major fundamental issues, and only then understand the finer details of DOS.

win98 itself comes with MSDOS7.0, that is, what you mentioned: entering it directly by pressing F8 or the ctrl key when win98 starts. Or shut down and restart to DOS. If you want to install an earlier version, such as DOS6.22, you can use a multi-system partitioning tool (PARTITION MAGIC、SFDISK、SPFDISK, etc.) to create another primary partition. Install DOS in the newly created primary partition.
WIN systems all have IO.SYS、MSDOS.SYS、COMMAND.COM、AUTOEXEC.BAT、CONFIG.SYS. You can modify them with Notepad, or use EDIT under DOS.
The DOS used from the WIN98 Start menu is an application program. It only simulates a DOS system; it is not a real-mode DOS, and it is restricted by the WIN system. The other situations you asked about are MSDOS7.0.

There is a special introduction in the site's "DOS Articles" section. You can download a packaged copy of the site's webpages here:
http://www2.zzu.edu.cn/ie/newdos/uploadImages/2002111722184894348.zip

Thanks to the two posters above.
In win98c:
on the drive there are IO.SYS、MSDOS.SYS、COMMAND.COM、AUTOEXEC.BAT、CONFIG.SYS
and in the registry msconfig also has these items. The contents seem to be different. What is the distinction here? What's the difference?

WIN98 is a graphical interface operating system with DOS as its kernel, so its initial boot method is the same as DOS7.1. And IO.SYS、MSDOS.SYS、COMMAND.COM、AUTOEXEC.BAT、CONFIG.SYS are the essential files for DOS startup (AUTOEXEC.BAT and CONFIG.SYS can be absent). That is to say, when these 5 files are loaded into memory, the DOS startup process of WIN98 is complete (if the first three files are missing, the computer will be unable to boot). Only then does WIN98 start its GUI (that is, the graphical interface system). At this point, the drivers for various hardware under the WIN system, the configuration and settings of various system files, fonts, and so on are loaded...
msconfig.exe is called the System Configuration Utility in Chinese. It is used to adjust the WIN system's software and hardware environment and its configuration settings, and also whether some application programs run when the system starts up. For example, QQ.
The registry is the database of the entire WIN98 system (including application programs). It contains detailed information about hardware and software, as well as file type associations. The normal operation of the whole WIN98 system is comprehensively controlled by the registry.
UNDERSTAND?

Learn how to ask questions first.
Change your post title to something better.
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