On April 25, 2024, Microsoft released the source code of MS-/PC-DOS 4.00 to the public, and the community managed to provide MS-DOS 4.01 as well.
While the original release was available as a set of six 5,25" floppy disks (and optionally three 3,5" disks for version 4.01), this open-source release does not have official installation media.
Recreating the original media would theoretically be possible, but I want to focus on the 720k images for this project. Having to swap around six floppies multiple times isn’t practical. Furthermore, we can build images for 1.44 MB floppy disks for increased compatibility—the SELECT utility used for the installation process doesn’t like it if you install it on floppies with a different format than the source disks are written in.
The open-source release is missing a few program files and the entire DOSSHELL environment, so we also have to deal with this.
