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I see. I don't see a lot of use for that, but it's still nice to know.

Quietust wrote:reading $2004 does not increment the address pointer ($2003) - only writing does that.

That's probably what allowed you to use $2004 for reverse-engineering the sprite fetch behaviour, right? I mean, if each one of your reads would increment the address, you'd pretty much screw the fetching process.

tokumaru wrote:I see. I don't see a lot of use for that, but it's still nice to know.

Quietust wrote:reading $2004 does not increment the address pointer ($2003) - only writing does that.

That's probably what allowed you to use $2004 for reverse-engineering the sprite fetch behaviour, right? I mean, if each one of your reads would increment the address, you'd pretty much screw the fetching process.

Not necessarily - the PPU uses a separate counter to address sprite memory during rendering, since $2003 affects how that counter is initialized on every scanline.