Microsoft releases the source code for MS-DOS v4.0 on GitHub
MS-DOS (MicroSoft Disk Operating System) was without a doubt one of the most pivotal operating systems back in the 80s and early 90s, with the very same operating system paving the way in user base and popularity into what we now know as Microsoft Windows, with MS-DOS even being included into initial releases of Windows 95, and still being supported up to the year 2000, with the final releases being alongside Windows ME.
Given the importance of the operating system in computer history, Microsoft originally released the source code for versions v1.25 and v2.0 of MS-DOS to their GitHub repository, making them open source, back in 2018, which according to Microsoft it was mainly done for education and experimentation for low-lever software programmers.
In April 25th, 2024, Microsoft has released yet another version of MS-DOS into their public repository, with the latest version to be included and publicly available being v4.0.
The current open source repository for MS-DOS works under the MIT license, and has been archived and marked for historical reference, so Microsoft will not accept any kind of pull requests nor modifications to the files on their repository, but users are able to fork the open source MS-DOS project and experiment on their own.
MS-DOS still has newer versions yet to become open source, since it goes all the way up to version v7.0 for Windows 95, and the last version known being v8.0 releases alongside WIndows ME, but until Microsoft decides, versions v5.0 up to v8.0 still remain as closed source.
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