Microsoft Launches Open-Source MS-DOS On GitHub

In Summary :

Four years ago Microsoft made public the source-code to MS-DOS 1.25 and 2.0 to the Computer History Museum. Today though they're making it much more accessible and friendly to modern developers by pushing it onto GitHub.

Microsoft has published the source trees to MS-DOS 1.25 and MS-DOS 2.0 on GitHub so that it's easier to find, read, and reference than the previous source drop. Microsoft will not be accepting pull requests or the like but rather is being treated as a static copy.

These versions of MS-DOS were written in 8086 Assembly and originate from the original 86-DOS release from 1980. [...]

kindly refer the following link as follow up :
https://www.phoronix.com/scan.php?page=news_item&px=Microsoft-MS-DOS-GitHub