Microsoft's 6502 BASIC is now Open Source (2025) (opens in new tab)

A subset of it?

I have a copy of "Tiny" Pascal by Supersoft from 1979 on a cassette tape which was licensed to Tandy Corp and which would load onto a 16KB TRS-80 Model III and allow a bit of room for programming.

One of the great regrets of my life is that when I was doing so and when it would have mattered, I was unaware of the patch for this which would have allowed it to be saved as an executable to a TRS-DOS disk....

Maybe they could have implemented a useful subset of Pascal.

Microsoft itself popularized BASIC on microcomputers with its 8080 BASIC, starting on the Altair and ported to everything with A, B, C, D, E, H, and L registers since.

Before then, however, BASIC was already popular on minicomputers as both an introductory language for beginners and a business language; the various "Business BASIC" dialects providing a small-business alternative to COBOL on mainframes with their features for decimal math and ISAM database access.

No, there was a big post somewhere on the previous release two weeks ago of the DOS source showing just how incredibly hard of a challenge it was to properly input/OCR all the reams of source was.

This source is a lot smaller, but still annoying if they had to type it all in or OCR it.

You don’t need an llm to do this.

From the video [1] that links to Ben Eater's fork with extensions and configuration specific to his 6502 breadboard computer [2]. That in turn is forked from `mist64/msbasic` which refers to a blog post [3] which states:

> This episode of “Computer Archeology” is about reverse engineering eight different versions of Microsoft BASIC 6502 (Commodore, AppleSoft etc.), ...

> This article also presents a set of assembly source files that can be made to compile into a byte exact copy of seven different versions of Microsoft BASIC, and lets you even create your own version.

So Ben Eater's version is based on a reverse engineered version of the same program. You should be able to adapt the code released here to run on Ben Eater's 6502 with a bit of work.

[1] https://www.youtube.com/watch?v=XlbPnihCM0E&list=PLowKtXNTBy...

[2] https://github.com/beneater/msbasic

[3] https://www.pagetable.com/?p=46

I've benchmarked Applesoft and Commodore BASIC quite a bit and they benchmark exactly the same, so I'm not surprised. Both systems run at 1.023 MHz in NTSC. Of course, they are both derived from Microsoft's 6502 BASIC. I'm sure they're not cycle exact but they are close enough that BASIC doesn't show any difference.