When a new update becomes available, Nintendo sends a message to connected systems notifying them of the available update.Several game discs, both first-party and third-party games, have included system software updates so that players who are not connected to the Internet can still update their system.
System updates are dangerous to a Wii console with homebrew installed to it; the update can "brick" the system or force you to restore the Homebrew Channel.You'll be able to keep the Homebrew Channel without having to update those games.Note: See How to Update Wii Channels If I Have Homebrew Installed if you need help doing that. To actually upgrade, use the steps on the Upgrade page after reading this page. It's slightly harder to install homebrew on 4.3 than on earlier firmwares.This is safe and the recommended way to upgrade the Wii, but only if you first take precautions (listed here). You can safely upgrade after installing homebrew, instead.
These control input and output between the code running on the main processor (the Power PC "Broadway" processor) and the Wii's hardware features that did not exist on the Game Cube, which can only be accessed via the ARM.