Microsoft has recently made available under an open-source license the source code of the MOS 6502 BASIC interpreter, a collaborative effort between Bill Gates and Rick Weland in 1976. Specifically tailored for the MOS 6502 processor, this interpreter boasts a compact size of 8KB and bears the version number 1.1. It served as a cornerstone for the BASIC language in the early days of personal computing, finding widespread adoption in models like the Commodore PET, VIC-20, and Commodore 64. This open-source initiative not only unearths a piece of computing history but also offers tech enthusiasts and researchers a treasure trove of resources to delve into the evolution of early computer languages. The source code files maintain their original file headers and even contain a whimsical Easter egg crafted by Gates himself.