Four years after working with the Computer History Museum to release the source code for MS-DOS, Microsoft is “re-open-sourcing” its command line operating system from the ’80s.

This time the company is making the source code for MS-DOS 1.25 and MS-DOS 2.0 available through GitHub.

The company says the files are the same, but posting them to GitHub makes it easier for people to “find, read, and refer to” if they’re hosted at the popular web-based version control/source code management platform.

While the source code is available for examination and use, Microsoft notes that the “files in this repo are for historical reference and will be kept static, so please don’t send Pull Requests suggesting any modifications to the source files,” but the company says developers can fork the repo and build and customize their own versions of MS-DOS.

While there are probably better alternatives available for folks that actually want to run old-school DOS applications on modern computers, the repository lets developers take a look at a piece of computing history.

via MSDN

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4 replies on “Microsoft releases MS-DOS source code to GitHub”

  1. Hi everybody, can I make a up and running msdos os using files available in github repository, that is:
    I’m creating IO.SYS by linking SKELIO + SYSINIT + SYSIMES object files. then I am copying IO. SYS, MSDOS.SYS and COMMAND.COM in a formatted CD. But I didn’t get success. Please guide.

  2. If MS was actually trying to be forthcomming instead of doing a hollow Publicity Stunt, they’d open-source MS-DOS 6.22 or 7 instead of 1.25 and 2.

    1. Sure, but can you even understand the code? Hint: It’s all in x86 assembly language. Do you even know how to download from Github? Do you have an assembler dev environment ready to compile a single DOS command, such as Actually don’t answer that, no one cares.

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