“Microsoft has open-sourced the version of BASIC it created in 1976 for the #MOS #6502 processor used in many early #microcomputers.

As the software colossus explained in a Wednesday post, Microsoft founders Bill Gates and Paul Allen wrote the company’s first product, BASIC for the #Altair8800 #microcomputer and the #Intel8080 #processor that powered it, in 1975.

A year later Gates and Ric Weiland, Microsoft’s second employee, ported Microsoft #BASIC to the #6502Processor.

In 1977, #CommodoreComputer licensed it for $25,000 and used #Microsoft #BASIC in its #PET, #VIC20, and #Commodore64 machines.”

source code <https://github.com/microsoft/BASIC-M6502/blob/main/m6502.asm> (6,955 lines)

#software / #assembly / #KLOC / #MITLicense <https://www.theregister.com/2025/09/04/microsoft_open_sources_6502_basic/>