Microsoft open-sourced MS-DOS 4.0.

[NON]

Originally Posted by WhoCares

Why doesn't MS open source the other versions of MS-DOS?

The "good" ones were the MS-DOS v3.30 and 5.0a. Even the version 6 was not so bad.
The v4.0 is the "bad" one. Much the Windows Vista, which was not well received by the community.
It's no wonder they did not want to release the source code of the "good" versions.

Unless officially released by Microsoft as open source, leaked sources cannot be used for any legit purposes.
Even the site with the leaked sources have mentioned this prominently:

I am already aware of the leaks. They are useless for me.
I need to be able to use the sources in software that I can sell!

It's true that I sell cracked software from my home. I am a hard-core pirate and I do not deny that.
But for software that I create to sell as developed software, I cannot use the code unless it is official open sourced.