View source for IOS4

{{Infobox IOS
| initialRelease = [[boot2v0]]
| update = [[3.3rev03]]
| version = v65280
| type = menu
| status = private
| stubvariant = 2008
}}
'''IOS4''' was a very primitive [[IOS]] that was used by both the [[Startup Disc Menu]] and the [[System Menu]] used in the factory process. This IOS and the System Menu come preburnt at the factory, before any other discs are inserted.

IOS4 has code for USB, SD, the disc drive, and USB Ethernet, but does not have code for [[WiiConnect24]] (which was added in [[IOS5]]), SSL, or WiFi.

Like [[IOS10]] and older versions of [[IOS9]], this IOS does not have a build tag.

U.S. update partitions are set to use this IOS in their [[TMD]]. Other regions are not yet known.

[[IOS3]] and IOS4 are also the only two [[IOS]]es stubbed on the [[Wii mini]], since most IOSes will hang on the Wii mini due to the WiFi module not responding.

The [[SDK]] version that uses IOS4 probably only supports 4:3 video; this is evident in the [[Wii Startup Disc]]'s SDK, which most likely uses IOS4.

Unlike most IOSes, IOS4 seems to do some verification of the TMD to be loaded involving [[:/sys/cert.sys]] when it starts up. The depth of this verification is not yet known, and it is not known why this code was removed from IOS9 and later.