45 years later, earliest DOS source code transcribed from a stack of old printouts found in a garage — code was open-sourced to mark 86-DOS 1.00’s anniversary

Microsoft has open-sourced transcribed source code for 86-DOS 1.00, early PC-DOS 1.00 components, and the Microsoft BASIC-86 Compiler runtime library on GitHub.

The code was recovered from old dot-matrix printouts found in Tim Paterson’s garage and checked to rebuild the original binaries.

The release marks the 45th anniversary of the system and adds a rare primary source for MS-DOS and PC-DOS history.

Historians, developers, and hobbyists now have a clearer look at the origins of one of the most important early PC operating systems.