Microsoft Releases MS-DOS Source Code on GitHub - https://news.ycombinator.com/item?id=18428882 - Nov 2018 (7 comments)

The original sources of MS-DOS 1.25 and 2.0 - https://news.ycombinator.com/item?id=18097661 - Sept 2018 (115 comments)

MS-DOS is now Open Source - https://news.ycombinator.com/item?id=7468192 - March 2014 (3 comments)

Microsoft makes source code for MS-DOS and Word for Windows available to public - https://news.ycombinator.com/item?id=7466952 - March 2014 (204 comments)

MS-DOS Source Code Released - https://news.ycombinator.com/item?id=7466826 - March 2014 (7 comments)