Microsoft has open-sourced the complete source code of its 6502 BASIC interpreter from 1978, which powered early personal computers like the Commodore PET and Apple II. The code, consisting of 6,955 lines, is available on GitHub for free use, modification, and distribution. This historical release aims to preserve knowledge of early computing for future generations, allowing enthusiasts and researchers to study its optimization techniques. Microsoft’s shift to open-source practices under CEO Satya Nadella contrasts with its previous stance against open source in the 1990s.
https://arstechnica.com/gadgets/2025/09/microsoft-open-sources-bill-gates-6502-basic-from-1978/