Microsoft is “re-releasing” the source codes for the MS-DOS 1.25 and 2.0 operating systems written in 1983.
One of the most important pieces of software in computer history, MS-DOS, an operating system developed and sold by Microsoft, is being re-released for a second time.
In 2014, the original source codes were transferred to the Computer History Museum. They were made available to the public, but their use in commercial projects and distribution on the web were prohibited.
However, this time the codes have been published under the MIT license, which allows you to modify, distribute, and use the codes freely in your products.
MS-DOS 1.25 and 2.0 are now available on GitHub for easy access by developers. But keep in mind that Microsoft will not accept pull requests and rather treats the code as a static copy.
These versions of MS-DOS were written in 8086 assembly code, and the original 86-DOS source codes date from December 29, 1980.
Microsoft also shared some interesting facts about the codes such as:
- The MS-DOS 1.25 code was written on May 9, 1983 and includes only 7 source files – including the original MS-DOS Command-Line shell – COMMAND.ASM!
- While MS-DOS 2.0 was written around August 3, 1983, which later increased significantly in size and became more sophisticated. It consisted of a total of 100 .ASM files.
For those who would like to see more interesting comments around the codes, they can check the documentation files (.TXT, .DOC) that are available along with the source and object files.
