Microsoft has released “BASIC for the 6502 microprocessor version 1.1” on Github under license from the Massachusetts Institute of Technology (MIT).
Almost half a century after Bill Gates created source code, now anyone can freely download it, modify it, distribute it, or even resell it. It’s worth noting, that derivatives of this version of BASIC formed the basis of several iconic computers, including Commodore 64.
Microsoft’s blog summarizes the history of BASIC and some key facts. BASIC was once the company’s first product, designed for the Intel 8080 processor. This programming language was created by Bill Gates and Paul Allen forAltair 8800 in 1975.
On Github BASIC code transferred by Bill Gates was released under the MIT license and Rick Weiland based on the MOS 6502 microprocessor and released in 1976. Interestingly, the commit date of the m6502.asm file and related Markdown documents is specified as July 27, 1978, long before Git was created. It’s not that complicated: you just need to make changes to the commit and submit the date.
The MOS 6502 assembly code became widespread and became the basis of BASIC, installed on the then Apple II, Commodore PET, VIC-20, and C64 computers. Subsequently, Commodore licensed BASIC for the 6502 platform, paying Microsoft $25 thousand. It may not seem like a lot of money, but according to Microsoft, it allowed millions of new programmers to get access to BASIC, while they were taking their first steps in coding.
The BASIC 1.1 version on GitHub supports Apple II, Commodore PET, Ohio Scientific (OSI), MOS Technology KIM-1, and PDP-10 Simulation. Microsoft adds that version 1.1 includes “a fix for the garbage collector discovered by Commodore and jointly implemented in 1978 by Commodore engineer John Feagans and Bill Gates when Feagans visited Microsoft’s Bellevue office.”
In total, the release contains 6,955 lines of assembly language code, that anyone can read and experiment with. Microsoft characterizes this BASIC interpreter as one of the most historically significant software of the early era of personal computers.
The company claims that the BASIC source code for the 6502 microprocessor version 1.1, which is available under a modern license, is based on an early version of GW-BASIC, which was originally shipped in the original IBM PC ROM, then evolved into QBASIC, and then Visual Basic.
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