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Microsoft open sources MS-DOS 4.0

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More open source surprises for you today, coming from Microsoft too which is always interesting to see as they've now open sourced MS-DOS 4.0.

Added into their existing MS-DOS repository on GitHub which already had MS-DOS v1.25 and v2.0, they've now expanded it to include MS-DOS v4.0 which was jointly developed by IBM and Microsoft. This is all available under the permissive MIT license.

From the repo:

The MS-DOS v1.25 and v2.0 files were originally shared at the Computer History Museum on March 25th, 2014 and are being (re)published in this repo to make them easier to find, reference-to in external writing and works, and to allow exploration and experimentation for those interested in early PC Operating Systems.

They're doing this for "historical reference and will be kept static" so they're not accepting pull requests, but that doesn't stop someone forking them and doing pretty much whatever they want now it's all under the MIT license. Great news for preservation.

It will be interesting to see if they eventually keep going adding in more later versions, and perhaps even get some earlier versions of Windows up too. Now that would truly be something don't you think?

There's a fun little tidbit of history in the Microsoft blog post on it with the code being found on some old floppy disks.

Article taken from GamingOnLinux.com.
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I am the owner of GamingOnLinux. After discovering Linux back in the days of Mandrake in 2003, I constantly came back to check on the progress of Linux until Ubuntu appeared on the scene and it helped me to really love it. You can reach me easily by emailing GamingOnLinux directly.
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19 comments
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whizse Apr 26
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Pinguino Apr 26
Oh, fun, let me see how that looks like. Maybe I can learn a thing or two.

(84,9% Assembly)

aaaaaaaaaaaaaaand nevermind.
Liam Dawe Apr 26
Quoting: whizse
One of my most favourite comments ever lmao
jordicoma Apr 26
At last! They only released 37 years late.
It should be mandatory to release the source code of all software after 10 years.
Ehvis Apr 26
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Quoting: PinguinoOh, fun, let me see how that looks like. Maybe I can learn a thing or two.

(84,9% Assembly)

aaaaaaaaaaaaaaand nevermind.

Haha, sometimes it pays to be old.

Had a quick peek. Nothing too special or unexpected of course. Kind of fun to see a different style between parts of code. But I see no use for it other than preservation.
lucinos Apr 26
We already have FreeDOS so MS-DOS is only for history. It would be more interesting to release Windows 3.1 as open source. This might actually happen. Also very interesting would be the release of windows 95. This unfortunately is very unlikely as I remember they have many legal complications. The last windows version I would care is windows 2000. After 2000 I would just prefer windows to simply vanish from existence.
Eike Apr 26
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The biggest surprise to me is that they actually still found the code.
rea987 Apr 26
Quoting: EikeThe biggest surprise to me is that they actually still found the code.

Microsoft is not Activision. Wait...
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MS-DOS 6.22 or bust (maybe in 10 years?)


Last edited by BloodScourge on 26 April 2024 at 11:30 am UTC
Woodlandor Apr 26
I’ve always wondered if some of them wouldn’t mind releasing source code for some old outdated software and then they look at the code… 😬 and see how much duct tape, popsicle sticks and bubble gum held it together and thought it would be a bad image 😂
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