[LocalH]

Games of that era tended to hit the hardware directly for I/O, meaning that there is no firmware that can enforce any such thing. AFAIK the Game Boy boot ROM just verifies the Nintendo logo data, plays the chime, then boots the game, and after the game boots, the boot ROM completely disappears from the memory map.

[Danieru]

Nintendo held onto this no os approach into the Wii era. Hence if you ran a japanese version game on a north American Wii you got the japanese Wii pause menu.

Meanwhile the PS3 and Xbox 360 had hypervisors.

[LocalH]

Well, the Wii did have an OS, that would receive updates over time. IOS was managed sort of shitty, though. Since older games would be linked with specific versions of IOS, they had to literally keep multiple versions of the OS around on NAND. They would occasionally stub out specific slots (usually those used by the System Menu, or by internal-only discs, or even slots they never used but that pirates did use).

Agreed, however, that all PPC code running during a game came from code on the disc, even "OS" things like the Home menu. The IOS code largely gatekept the advanced Wii features as compared to the GC

[mikepurvis]

Yeah, I remember that too— each game was shipping its own instance of the pause menu, so they would have subtly different behaviour, including around weird things like what the light on the disk drive did.

I imagine this kind of thing is also why the backcompat story for playing Wii games on a Wii U is so janky— you have to access them through the "vWii" environment, which I guess is basically just a kind of VM, so that it can provide a virtualized instance of the hardware that the game ROMs/discs are expecting to talk to.