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.
Sadly nothing in Scott's blog post about how they obtained the source. Was it still in Microsoft's archives? Did they happen upon some tractor-feed print-outs they had to type in by hand?
It would also be interesting why it was open-sourced now. I assume if they had done the same last year, the resulting loss of revenue would not have destroyed the plucky little $3T upstart.
In 1979, I made a program called VisiBase in this BASIC.
It's a visual database modeled after VisiCalc.
That won me a joystick in at a competition by the local computer store. :-)
Still have the source, that works in an Apple 2 emulator. It's 13 K in ASCII (untokenized).
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....
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.
Except that wasn't possible. Languages like BASIC and Forth exist because they were the only kind of language implementable in 4K with no disk. Pascal in its smallest form (UCSD p-system) still needed disk overlays. The smallest C compilers were poly phase, needing storage for intermediate state.
I am really torn about this. Sure Microsoft is doing a lot of open source today (.NET core, VS Code and a bit of historic curiosities such as this one) but the "open letter to the hobbyists" still stands :) Release the Windows source code then we are talking.
The Apple ][ basic interpreter placed its "get next token" routine down in the first 255 bytes of the computer's memory. Being there allowed for the machine instructions to be fetched twice as fast as "high memory". And "get next token" is definitely a good guess for hotpath.
rhdunn | 3 hours ago
[1] https://www.youtube.com/playlist?list=PLowKtXNTBypFbtuVMUVXN...
BeefySwain | 3 hours ago
rhdunn | 2 hours ago
> 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
qingcharles | 3 hours ago
bdcravens | 3 hours ago
dhosek | 2 hours ago
bdcravens | an hour ago
chihuahua | 3 hours ago
Smalltalker-80 | 3 hours ago
homarp | 2 hours ago
rbanffy | 3 hours ago
WillAdams | 2 hours ago
https://www.folklore.org/MacBasic.html
amichail | 3 hours ago
xxs | 3 hours ago
amichail | 3 hours ago
bitwize | 2 hours ago
WillAdams | 2 hours ago
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....
SoftTalker | 2 hours ago
bitwize | 2 hours ago
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.
dboreham | an hour ago
ofrzeta | 2 hours ago
PxP_ | 2 hours ago
zendist | 2 hours ago
dang | 2 hours ago
Microsoft BASIC for 6502 Microprocessor – Version 1.1 - https://news.ycombinator.com/item?id=45118392 - Sept 2025 (198 comments)
Related ongoing thread:
Microsoft open-sources "the earliest DOS source code discovered to date" - https://news.ycombinator.com/item?id=48253386 - May 2026 (110 comments)
rbobby | an hour ago