I understand how the ‘minus world’ glitch works, and that there are hundreds of other levels. What I can’t find much of is how the game actually loads level data. Where is the information for the 7-2 clone in 36-1 coming from? Why are some other inaccessible levels just infinite pits?

EDIT: from this video, we can see there are glitched tiles far enough beyond the flagpole (

). Where is this information coming from? Is Mario exploring memory at this point?

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    This is something I've wondered about too. The basic idea of the minus world is that it starts with a garbage pointer pointing to world 36-1, but why exactly is there a copy of 7-3 at the theoretical memory location of 36-1? Weren't cart sizes drastically limited in those days? Why is there all this extra space dedicated to glitchy versions of the real/final levels? This makes me think there is more too it than just a bad pointer. Commented Jun 8, 2022 at 10:24
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    @RobertColumbia, it's more than just a bad pointer, it's also data types with small maximum values. If you add 256 to a one-byte value, or 65536 to a two-byte value, it wraps around and you get your original value back.
    – Mark
    Commented Jun 8, 2022 at 20:04


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