China DOS Union

As the title says

Basically they are compatible, but many are not fully compatible. For example, ROM-DOS 7.10, FreeDOS, PC-DOS 7.10, and other DOS systems are all currently moving closer to compatibility with MS-DOS 7.10.

Is FreeDOS the only free one among these DOS systems? (I need to choose an operating system now for a commercial system, so there must not be any copyright issues.)

Many versions of DR-DOS and other DOS systems are completely free for personal users to use (that is, Free for personal users), but for commercial use, I guess only FreeDOS qualifies.

I have a question: why doesn't Super DOS downloaded here use the FreeDOS kernel? After all, MS-DOS belongs to Microsoft. There could be copyright issues later when it is put into use.

The following is quoted from warm's post on 2003-10-23 13:16:32:
I have a question: why doesn't Super DOS downloaded here use the FreeDOS kernel? After all, MS-DOS belongs to Microsoft. There could be copyright issues later when it is put into use.

Mainly out of compatibility considerations... At present, MS-DOS naturally has the strongest functionality and compatibility, while FreeDOS is still under continuous development. Let's wait until it becomes stable before using FreeDOS as the kernel.

This is how I see it: since I use FreeDOS for some simple control purposes, I only need to be able to boot DOS's 3 core files (I don't need things like HIMEM, UMB, DOSKEY, SMARTDRV, etc.; I feel the fewer things running, the more stable it is), and then run the program I wrote myself. So as long as the core is stable, that's enough.

As far as you know, what compatibility problems does FreeDOS currently have?

FreeDOS's core files are updated rather quickly, generally once every two or three months or every few months, but it is still in beta all the time right now, so for the time being its stability is still hard to guarantee, especially for the "Super DOS Boot Disk" (after all, the "Super DOS Boot Disk" has to include quite a lot of functions, and once the DOS kernel itself has compatibility problems, then all the problems come at once). To give an example, FreeDOS still cannot boot Windows 3.1/3.2, and that is a very typical compatibility problem.