Microsoft released MS-DOS 1.25 and 2.0 through the Commuter History Museum a few years ago. Now the company has broadened the release of these 1980s operating systems by putting g the software on GitHub.
The broader release of MS-DOS probably won't make a huge difference to many people but it's an interesting development that will help software creators get some insights into the history of development and how Microsoft's engineers solved the challenges of the day when it came to managing limited memory, processing and storage availability.
One of the fun things to do is to look at the comments developers made through readme files and comments in the code. Microsoft says "There are some interesting documentation (.TXT, .DOC) files interspersed with the source and object files - many are well worth a read, as are many of the source code comments!".
You can find the source code at GitHub.