Microsoft has announced the release of the sources of GW-BASIC, the programming language that was part of the MS-DOS operating system up to version 4. They were made available on the GitHub website under the free / open source MIT license. Microsoft will not accept requests for changes sent through the GitHub system, but anyone can freely not only go to read the assembly code but also experiment with it, probably using a virtual machine. The published sources date back to February 10, 1983, and, as for versions 1.25 and 2.0 of the MS-DOS operating system released in September 2018, this was done for historical and educational reasons.