Shoot that does sound like “no one can read it” .. sorry I mean “no modern OS”. I fixed it, thank you!
And yes tons of folks replicate MacPaint. I hope it didn’t sound like I was saying I was the first to think of it. I wanted to document the process of using CC to port it. The fact that it made something my kids love is super satisfying
I wanted to too how far I could get porting an old Macintosh application to run on a modern Mac.
The Computer History Museum released MacPaint's original source code years ago (Pascal + 68k assembly). I pointed Claude Code at it with a feasibility plan built in Gemini, and let it go. I didn't write or read any of the code it produced.
My favorite moment: it needed the tool icons, which live in the resource fork of the original binary. The disk image was MFS — Apple's pre-HFS filesystem from 1984. Nothing reads it. So it wrote an MFS parser, decoded the resource fork, and pulled the icons out.
And after one or two bug reports, I got the original screen up and running.
I know this isn't super exciting news for anyone, but as a senior software engineer, I've been feeling the same waves of excitement and existential dread over the improvements of coding models. This little side project made me smile.
The whole thing runs on iPad now. My kids use it every day and fight over who gets to print next.
I've had this project gathering a light layer of dust in my home directory for a couple months now. I used Gemini Deep Research to help produce the library, and I included the LLM-generated markdown for anyone who wishes to reproduce on other languages, improve upon it, etc.
And yes tons of folks replicate MacPaint. I hope it didn’t sound like I was saying I was the first to think of it. I wanted to document the process of using CC to port it. The fact that it made something my kids love is super satisfying