We just open-sourced DOS 4 (and found binaries of Multitasking DOS 4) https://www.hanselman.com/blog/open-sourcing-dos-4
Open Sourcing DOS 4

See the canonical version of this blog post at the Microsoft Open Source Blog! ...

@shanselman well... I just... um... WOW.

This is actually HUGE for the retro community! Like... monumental! Because this is recognition.

Ku-DOS!