Allow me to geek out a little. I love this stuff. According to [1] Kirby uses the Nintendo MMC-3 mapper [2], which brings some nifty features like a scanline

Allow me to geek out a little. I love this stuff. According to [1] Kirby uses the Nintendo MMC-3 mapper [2], which brings some nifty features like a scanline counter. This can be used for finer control of scrolling regions/screen splitting (horizontal only). The scanline counter, alongside the swappable PRG banks and a theoretical max ROM size of 3216 CHR + 328 PRG = 768Kb enabled developers to really push the system to its limits, with advanced scroll tricks, providing for impressive parallax scrolling (while also presenting a status bar). The CPU was still a limitation though. Some late NES games were at least partially written in C (at least you can see C format strings in some of the Koei strategy games), but it was mostly fine tuned, hand coded, 100% organic 6502 assembly. As for mappers, there are more advanced ones, like the MMC5 (which enables things like 8x8 color regions, scanline IRQs and expandable memory), but no game ever really took advantage of it. Maybe a matter of keeping optins open in case they had to switch to another mapper for cost cutting measures, dunno. -- [1] https://nesdir.github.io/D7794AFC_USA.html https://nesdir.github.io/D7794AFC_USA.html [2] https://wiki.nesdev.org/w/index.php/MMC3 https://wiki.nesdev.org/w/index.php/MMC3