Microsoft open-sources Bill Gates’ 6502 BASIC from 1978 arstechnica.com/gadgets/2…

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. (https://github.com/microsoft/BASIC-M6502)

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. […] 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.

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.