In 2018 we (re)-open-sourced MS‑DOS 1.25 and 2.11, and more recently in 2024 we were able to make the source for MS‑DOS 4.0 available to the public as well. Today, on 86-DOS 1.00’s 45th anniversary, we’re continuing that tradition with the earliest DOS source code discovered to date.
Microsoft’s Open Source Programs Office (OSPO), Team Xbox, and Activision are making Zork I, Zork II, and Zork III available under the MIT License.
For decades, fragments and unofficial copies of Microsoft’s 6502 BASIC have circulated online, mirrored on retrocomputing sites, and preserved in museum archives. Coders have studied the code, rebuilt it, and even run it in modern systems. Today, for the first time, we're officially releasing it under an open-source license.
In partnership with IBM, we’re releasing the source code to MS-DOS 4.00 under the MIT license to support open innovation.
