Microsoft's 6502 BASIC Is Now Open Source

alternative_right writes: For decades, fragments and unofficial copies of Microsoft's 6502 BASIC have circulated online, mirrored on retrocomputing sites, and preserved in museum archives. Coders have studied the code, rebuilt it, and even run it in modern systems. Today, for the first time, we're opening the hatch and officially releasing the code under an open-source license. Microsoft BASIC began in 1975 as the company's very first product: a BASIC interpreter for the Intel 8080, written by Bill Gates and Paul Allen for the Altair 8800. That codebase was soon adapted to run on other 8-bit CPUs, including the MOS 6502, Motorola 6800, and 6809.

The 6502 port was completed in 1976 by Bill Gates and Ric Weiland. In 1977, Commodore licensed it for a flat fee of $25,000, a deal that placed Microsoft BASIC at the heart of Commodore's PET computers and, later, the VIC-20 and Commodore 64. The version we are releasing here -- labeled '1.1' -- contains fixes to the garbage collector identified by Commodore and jointly implemented in 1978 by Commodore engineer John Feagans and Bill Gates, when Feagans traveled to Microsoft's Bellevue offices. This is the version that shipped as the PET's 'BASIC V2.' It even contains a playful Bill Gates Easter egg, hidden in the labels STORDO and STORD0, which Gates himself confirmed in 2010.

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