Comparative C64 ROM Disassembly Study Guide

The Commodore 64 ROM has been subject to immense reverse engineering. Many commented disassemblies were published over the decades, scattered over different media such as books, magazines, disks, and later, the internet – and there are even some commentaries that apply to the C64 ROM, but were written with other systems in mind that shared Microsoft’s BASIC interpreter.

In the past weeks, I have collected and published several of these comentaries in a unified format:

Wouldn’t it be nice to see the comments of all these sources at the same time when looking up code in the C64 ROM?

At, you can now see a cross-referenced HTML of the disassembled C64 ROM, with four commentaries side-by-side – the Comparative C64 ROM Disassembly Study Guide:

If you can’t fit all columns on your screen, try reducing the text size in your browser.

The raw txt files with the commentaries as well as the script to combine them are maintained at Improvements welcome.

And, as mentioned previously, there are many more commentaries in existence, if you want to help me convert them into the canonical format, send me an email.

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