Commodore BASIC V2 open-sourced

[ScottishColin]

https://arstechnica.com/gadgets/2025/09/microsoft-open-sources-bill-gates-6502-basic-from-1978/

WAIT 6502,10

Colin.

[ortek_service]

Thanks for the info.

I presume, as it was written in assembler originally, then it had already been disassembled and commented a long time ago?

Even more-useful, Microsoft had actually originally-used 'conditional-compilation (or should that be called Assembly)'

With: https://github.com/microsoft/BASIC-M6502 saying

3. Multi-Platform Compatibility
This single codebase was designed to run on multiple different computer systems of the era
The conditional compilation system allowed the same source code to target different hardware platforms
This approach influenced how software would be developed for decades to come

And:

Supported Computer Systems
The source code includes conditional compilation support for multiple pioneering computer systems:

Apple II (REALIO=4) - Steve Jobs and Steve Wozniak's revolutionary home computer
Commodore PET (REALIO=3) - One of the first complete personal computers
Ohio Scientific (OSI) (REALIO=2) - Popular among hobbyists and schools
MOS Technology KIM-1 (REALIO=1) - An influential single-board computer
PDP-10 Simulation (REALIO=0) - For development and testing purposes

Technical Specifications
Language: 6502 Assembly Language
Target Processor: MOS Technology 6502 8-bit microprocessor
Memory Footprint: 8KB ROM version
Features: Complete BASIC interpreter with floating-point arithmetic
Architecture: Designed for both ROM and RAM configurations

So also useful for the Apple-II etc, it can be assembled for.

I also note, in MS's change of approach to Open-Source (I've only just discovered they've owned GitHub since 2018), that they've also released the source-code for the PC's original GW-BASIC. So maybe can look forward to many vintage MS products getting their source-code released.

It is surprising that they've actually kept all of this, as many companies seem to abandon their archives of support info after a few years, responding that they don't hold this anymore when people make enquiries.

[Timbucus]

They had lost the 6809 version - that was the effort we did a few years ago at the Dragon 40th event in Port Talbot to scan in a copy from possibly the only printout of it that had resided in the attic of the Dragon ROM developer Duncan Smeed.

You can see him and the recovery effort here at about 4mins in https://youtu.be/od2Up_4j5Xo

Then David Lindsey (with some help from others) who works for MS cleaned it all up and presented back to MS - so that is also on github https://github.com/davidlinsley/DragonBasic