Microsoft puts MS-DOS 1.25 and 2.0 on GitHub

Microsoft has released the source code for MS-DOS versions 1.25 and 2.0 on GitHub. The code is open sourced under license from MIT. This means that anyone who wants can share, modify and apply the source code in their own code.

According to the description on GitHub, the source code and binaries in the repository have not been changed. The publication was done because of its historical value. The versions of the MS-DOS source code are free to use for everyone. The reason for putting the source code on GitHub is to make it easier to find.

It is not the first time that Microsoft has released the source code of the OS. In 2014, the US Computer History Museum was allowed to publish the code for MS-DOS 1.1 and 2.0 for educational purposes. This was done under a stricter own license.

MS-DOS 1.25 and 2.0 are written in 8086 assembly language, and the 86-DOS source code on which they are based is dated December 29, 1980. In August of that year, Seattle Computer Products released the first version of 86-DOS, created by programmer Tim Paterson. MS-DOS 1.25 itself is dated May 9, 1983 and consists of seven source files. The 2.0 version was written three months later and over time included a hundred .asm files.