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    Even Super Mario Brothers basically uses the same technique. It will never get past drawing the score at the top when Sprite-0-Hit isn’t implemented. Since this feature is mostly only useful for determining a whether the PPU passed a certain position, i highly suspect this is very much intended behaviour.

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      Have you read the complete article? The undefined behaviour is about writing to the PPUADDR while the screen is rendering to smooth vertical scrolling with split screen. Actually pretty interesting dive into how the NES PPU internally work and shows visual glitch in Zelda that would be explained by the limitation of the undefined behaviour.