Originally posted by: aupton
as if the CHR isn't booting
The PPU can't "boot" anything, the NES doesn't work like that. The CPU is in charge and it needs PRG ROM data (and PRG RAM sometimes) in order for the NES as a whole to do anything. The PPU works passively along side the CPU, loading whatever it can find off the cartridge whether it's correct or not. When an NES game crashes, it's the CPU that crashes. The PPU can't crash, the worst that can happen is it loads wrong data, which it doesn't care about.