Hackmii News - IOS: history, build process

Bushing posted this over at Hackmii:

Another nerdy post, sorry. I want to talk about this “unsoftmoddable Wii” crap, but I need to go into some background first.

I’ve written in the past about IOS — or at least I’ve meant to — but it seems especially relevant now.

IOS probably stands for “Input/Output System” — because that’s what it does. It regulates I/O between the Broadway (PPC) and most of the rest of the Wii’s peripherals. It seems to have been written mostly from scratch by BroadOn.

Generally, when we talk about IOS, we mean the “firmware” that runs while normal code (game, system menu, etc) is running on the PPC. However, the same codebase is used to build boot2, boot1 and arguably even boot0! You can almost think of it as a set of matroshka dolls:

boot0 – ~1.4K
boot1 / BC – ~ 17K
boot2 – ~160K
IOS (multiple versions) – ~ 1.8MB each

More details --> http://hackmii.com/2009/06/ios-history-build-process/