Disassembled ROM sources for Macintosh 128K, 512K, and Plus

jonathanschilling

New Tinkerer
Apr 30, 2026
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Hi everyone,

Recently, I took another look at the disassembled sources of the Mac Plus ROM and wondered whether modern AI tools could be used to build a fully commented source tree from them.

As you might imagine, this got a bit out of hand, and after a few nights, this now exists:


It is a fully commented source tree from which the ROMs for the Macintosh 128K, 512K, and Plus (in all three versions) can be assembled using currently available open-source tools.

The Makefile also tests after assembly whether the generated ROM files match the original ROMs bit-for-bit.

Maybe this will be interesting to some of you here for debugging or hacking :)

I would be very happy to receive feedback, especially on the accuracy of the comments in the code, since I can only judge their quality moderately well.

Best regards,
Jonathan