I know not 6502 and there's a disassembly out there, but Bill Gates released a scanned PDF of the Original Altair BASIC Source:
https://www.gatesnotes.com/home/home-pa ... ource-code
50Years ago: Bill Gates released Original Altair BASIC Sourc
50Years ago: Bill Gates released Original Altair BASIC Sourc
ROR A? Where we're coding, we don't need A.