Category:Mappers with scanline IRQs

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Mappers in this category have the ability to schedule an IRQ an arbitrary and continuously-adjustable number of scanlines in the future. This is triggered in response to a rendering signal such as PPU A12.

Mappers with configurable cycle-based IRQs can simulate a scanline-counter by waiting an equivalent number of CPU cycles, but have less robust horizontal timing, since they will fire relative to their start time, rather than relative to a rendering signal. The VRC IRQ has a convenient mode for this.

Mappers with a fixed delay (but still clocked by the PPU) should go in the fixed-timing category instead.