Microsoft opened the code for 6502 BASIC, a version of the BASIC programming language originally written by Bill Gates and Paul Allen in 1975 for the Intel 8080 processor. In 1976, Gates and Rick Weiland adapted the code to work with other 8-bit chips, including the MOS 6502, which was used in the NES, Atari 2600, and many other devices.
Fragments and unofficial copies of the code have been circulating on the Internet and in museum archives for decades, and interest in the language continues to this day, so the company has decided to make the code open source. A version of BASIC M6502 8K VER 1.1 is available on GitHub, which, in particular, was the basis for Applesoft BASIC in Apple II computers.
"In 2025, interest is as strong as ever. The retro-computing scene is thriving, with FPGA-based re-creations, emulator projects, and active development communities. The Commodore brand has returned with the announcement of a new FPGA-powered Commodore 64, the first official Commodore hardware in decades," the company's blog reads.
In 1977, Commodore paid $25,000 to license the Microsoft BASIC code. This language became the basis for the Commodore PET computers, and later the VIC-20 and Commodore 64. This decision made BASIC the standard for Commodore computers and opened the way for millions of beginners to programming through simple commands such as 10 PRINT "HELLO" or 20 GOTO 10.
Version 1.1, released by Microsoft, includes a fix for the garbage collector. It was defined and implemented jointly by Commodore engineer John Figans and Bill Gates in 1978, when Figans visited Microsoft's Bellevue offices. It even contains a Bill Gates Easter egg hidden in the STORDO and STORD0 tags, which Gates himself confirmed in 2010.