Ios56-64-v5661.wad -

You must obtain the file legally by "packing" it from Nintendo’s servers using a PC tool. NUS Downloader (NUSD) Open NUSD and ensure "Pack WAD" is checked. Navigate to:

: Refers to Input/Output System 56, an official operating system branch developed by Nintendo to handle USB storage, disc drive speed, and network accessories.

Crucially, for using it as a base for a cIOS, the specific version ( 5661 vs 5662 ) is often interchangeable. In a forum thread, a user confirmed that ios56-64-v5662 works as a base for installing cIOS, indicating the newer version is typically compatible when the older one is unavailable.