Historic interpreter taught millions to program on Commodore and Apple computers.
On Wednesday, Microsoft released the complete source code for Microsoft BASIC for 6502 Version 1.1, the 1978 interpreter that powered the Commodore PET, VIC-20, Commodore 64, and Apple II through custom adaptations. The company posted 6,955 lines of assembly language code to GitHub under an MIT license, allowing anyone to freely use, modify, and distribute the code that helped launch the personal computer revolution.
"Rick Weiland and I (Bill Gates) wrote the 6502 BASIC," Gates commented on the Page Table blog in 2010. "I put the WAIT command in.". //
At just 6,955 lines of assembly language—Microsoft's low-level 6502 code talked almost directly to the processor. Microsoft's BASIC squeezed remarkable functionality into minimal memory, a key achievement when RAM cost hundreds of dollars per kilobyte.
In the early personal computer space, cost was king. The MOS 6502 processor that ran this BASIC cost about $25, while competitors charged $200 for similar chips. Designer Chuck Peddle created the 6502 specifically to bring computing to the masses, and manufacturers built variations of the chip into the Atari 2600, Nintendo Entertainment System, and millions of Commodore computers. //
Why old code still matters
While modern computers can't run this 1978 assembly code directly, emulators and FPGA implementations keep the software alive for study and experimentation. The code reveals how programmers squeezed maximum functionality from minimal resources—lessons that remain relevant as developers optimize software for everything from smartwatches to spacecraft.
This kind of officially sanctioned release is important because without proper documentation and legal permission to study historical software, future generations risk losing the ability to understand how early computers worked in detail. //
the Github repository Microsoft created for 6502 BASIC includes a clever historical touch as a nod to the ancient code—the Git timestamps show commits from July 27, 1978.
