Microsoft is “re-releasing” the source codes for MS-DOS 1.25 and 2.0 operating systems that were written in 1983.
One of the most important software in computer history, MS-DOS, an OS developed and sold by Microsoft, has been opened for the second time.
In 2014, the original source codes were transferred to the Computer History Museum. It was publicly available with a ban that prohibited its use in commercial projects and distribution on the Web.
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 is now available on GitHub for easy access of developers. But keep in mind that Microsoft will not be accepting pull requests and it rather treats the codes as a static copy.
These versions of MS-DOS were written in 8086 assembly code and the initial 86-DOS source codes date back to December 29th, 1980.
Microsoft also shared some interesting facts about the codes such as:
- MS-DOS 1.25 codes were written back on May 9th, 1983, and comprises of 7 source files only — including the original MS-DOS Command-Line shell – COMMAND.ASM!
- Whereas the MS-DOS 2.0 was written around August 3rd, 1983, which later grew considerably in size and sophistication. It comprised of 100 .ASM files in total.
For those who would like to see more interesting source code comments can check out the documentation (.TXT, .DOC) files that are available with the source and object files.