everything in most cartridge based consoles is on a bus. CPU, SPU, RAM, ROM, whatever, it’s all on the same communication channel. the SNES didn’t have 3D capabilities but some games like Starfox had a GPU in the cartridge. there are modern mods for the NES that add a raspberry pi on the bus which allows it to do full motion video.
everything in most cartridge based consoles is on a bus. CPU, SPU, RAM, ROM, whatever, it’s all on the same communication channel. the SNES didn’t have 3D capabilities but some games like Starfox had a GPU in the cartridge. there are modern mods for the NES that add a raspberry pi on the bus which allows it to do full motion video.