Back in 2014, Microsoft open sourced MS-DOS as part of a collaboration with the Computer History Museum. Last week, Microsoft has re-open-sourced MS-DOS on GitHub. The new repo contains the original source-code and compiled binaries for MS-DOS 1.25 and MS-DOS 2.0. Microsoft is making this move so that MS-DOS source code will be easier to find, reference-to in external writing and works, and to allow exploration and experimentation for those interested in early operating systems. Microsoft also highlighted some interesting things about MS-DOS.
- All the source for MS-DOS 1.25 and 2.0 was written in 8086 assembly code
- The source code for the initial release of 86-DOS dates from around December 29th 1980
- The MS-DOS 1.25 code dates from around May 9th 1983, and is comprised of just 7 source files, including the original MS-DOS Command-Line shell – COMMAND.ASM!
- MS-DOS 2.0 dates from around August 3rd 1983, and grew considerably in sophistication (and team size), and is comprised of 100 .ASM files
- 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!
Check out the GitHub repo here.