Changes

IOS is not a "hypervisor", as it runs on a dedicated, separate CPU. However, IOS does isolate its memory from access by the main [[Hardware/Broadway|Broadway]] CPU, has the ability to reboot (and hence bootstrap) it, and is designed to be secure if the PowerPC side is compromised (although in practice many exploits have been found). In that sense, IOS is higher in the security hierarchy than code running on the PowerPC.

IOS is not a "hypervisor", as it runs on a dedicated, separate CPU. However, IOS does isolate its memory from access by the main [[Hardware/Broadway|Broadway]] CPU, has the ability to reboot (and hence bootstrap) it, and is designed to be secure if the PowerPC side is compromised (although in practice many exploits have been found). In that sense, IOS is higher in the security hierarchy than code running on the PowerPC.

Since the IOS API is largely forwards-compatible, it is often possible (though not recommended) to run official software with an alternate IOS branch or slot. Homebrew software will often run under a relatively large range of IOS versions, sometimes constrained by requiring newer features (e.g. USB EHCI support).

Since the IOS API is largely forwards-compatible, it is often possible (though not recommended) to run official software with an alternate IOS branch or slot; [[BC-NAND]] takes advantage of this so that IOS does not need to be reloaded a second time every time a [[title]] is launched. Homebrew software will often run under a relatively large range of IOS versions, sometimes constrained by requiring newer features (e.g. USB EHCI support).

When the Wii is in WiiConnect24 standby mode (yellow LED), the main PowerPC CPU is off, but IOS is still running.

When the Wii is in WiiConnect24 standby mode (yellow LED), the main PowerPC CPU is off, but IOS is still running.