Microsoft has open-sourced the earliest known version of DOS, predating even the MS-DOS branding, including the 86-DOS 1.00 kernel and utilities like CHKDSK. This release provides historical insight into the foundational software that powered early IBM PCs and clones. The code was digitally reconstructed by preservationists from physical printouts, as it was originally stored offline.
Background
MS-DOS was the foundational operating system for IBM PCs and clones, originating from 86-DOS developed by Tim Paterson and later acquired by Microsoft. Previous source releases by Microsoft have covered later versions of DOS.
- Source
- Ars Technica
- Published
- Apr 30, 2026 at 10:20 PM
- Score
- 6.0 / 10