Stacey Haffner articles

A close-up of Stacey Haffner, Director of OSPO at Microsoft.
Stacey Haffner
Director, Microsoft OSPO
Stacey Haffner is the Director of Microsoft's OSPO and a developer advocate, where she focuses on open source, AI, and the future of developer tools. For over a decade she's been a product leader, builder, and teacher, working across startups and big tech on .NET, Xbox, Unity, and much more. She's also an independent game developer and teaches on YouTube at youtube.com/@staceyhaffner.
2 min read

Continuing the story of early DOS development 

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.