Late last week, Microsoft released the complete source code for Microsoft BASIC for 6502 Version 1.1, the 1978 interpreter that powered early personal computers like the Commodore PET, VIC-20, Commodore 64, and Apple II. The company made the 6,955 lines of assembly language code available on GitHub under an MIT license, letting anyone freely use, modify, and distribute the software that played an important role in the early years of home computing.
Microsoft BASIC was millions of people's first programming experience in the late 1970s and early 1980s. By typing simple commands and creating small programs, users could directly control a computer for the first time.
Microsoft's release includes the updated Version 1.1 code, which was completed in 1978 through work by Microsoft founder Bill Gates and Commodore engineer John Feagans. This version included bug fixes and improved memory management. It was later released as "BASIC V2" for Commodore systems.
In 1977, Commodore licensed BASIC for $25,000 as a one-time payment, securing perpetual use without royalties. That deal helped millions of Commodore computers ship with Microsoft software at no further cost, a decision that later benefited Commodore and limited Microsoft, Ars Technica reports .
But funnily enough, the code includes documented Easter eggs attributed to Bill Gates, like the famous WAIT 6502,1 command. Running this command on a Commodore PET makes "MICROSOFT!" appear on the screen.
The release on GitHub includes historical commit timestamps set to July 27, 1978, years before Git was invented.
By offering official access to BASIC, Microsoft is helping preserve a piece of computing history.
