Microsoft BASIC for 6502 is the original assembly-language source code for Microsoft’s BASIC interpreter version 1.1, written for the MOS Technology 6502 8-bit microprocessor back in the late 1970s. It was used on pioneering personal computers (such as the Apple II, Commodore PET, etc.), enabling users to write and run programs in BASIC on those systems. The repo contains the full source (in 6502 assembly), with support for multiple hardware platforms via conditionals, includes floating-point arithmetic, string handling, arrays, math functions, I/O, etc. The repository is maintained by Microsoft, is archived (read-only), and released under the MIT license.

Features

  • Full BASIC interpreter implementation (including parsing, statement execution, branching, loops, etc.)
  • Floating-point arithmetic routines for computations beyond integer math
  • String handling and manipulation (strings, concatenation, etc.)
  • Arrays support (for both numeric and string arrays)
  • Conditional compilation / platform abstraction to support several early systems (e.g. Apple II, PET, OSI, KIM-1)
  • Compact code size designed for 8-bit memory constrained systems; memory-efficient implementation in assembly

Project Samples

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License

MIT License

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Additional Project Details

Operating Systems

Windows

Programming Language

Assembly

Related Categories

Assembly Programming Languages

Registered

2025-09-22