Microsoft Open-Sources Early MS-DOS Versions, This Time to GitHub

Posted on October 2, 2018 by Paul Thurrott in Dev, Microsoft with 9 Comments

Microsoft this week announced that it has “re-open-sourced” MS-DOS 1.25 and 2, this time to GitHub. The releases follow any earlier open-sourcening, ahem, via the Computer History Museum in 2014.

“We’re re-open-sourcing MS-DOS on GitHub because it’s much easier to find, read, and refer to MS-DOS source files if they’re in a GitHub repo than in the original downloadable compressed archive file,” Microsoft’s Rich Turner explains. “The source files are being (re)published for historical reference purposes and to allow exploration and experimentation for those interested in early PC operating systems [only].”

That last bit refers to the fact that GitHub is often used for open-source projects where others can make “pull requests,” which are suggestions for modifications. Obviously, Microsoft has no intention of modifying this code.

The MS-DOS source code was written entirely in 8086 Assembly Language and dates back to 1980. So you’ll want to fire up your dusty copy of MASM while strolling done memory lane.


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