Wii cIOS Explained

Question 1: What is cIOS?

cIOS either stands for Custom Input/Output System or Custom Internal Operating System. I tend to get the feeling that it actually means Custom Input/Output System because of what it does. cIOS is quite simply a modified/patched Nintendo system IOS.


Question 2: OK, so what's an IOS?

Now we start to get into the nuts and bolts. Despite popular belief, an IOS is NOT the firmware built into the Wii. In fact, as far as I can tell, there is no firmware built into the Wii, except for what is built into the DVD Drive itself. For those of you who aren't particularly tech savvy, Firmware is a piece of very low-level code that communicates directly with hardware. You can think of it like this: Hardware<->Firmware<->Software. All computers use firmware to directly control hardware. Most software takes advantage of easy to use calls to hardware, with the heavy lifting accomplished by the firmware. For instance, when a software designer needs to detect if there is a CD in a CD/DVD Drive, they code a call to the firmware, which in turn actually asks the drive if there is a disc and returns the answer to the software.



As stated previously, the IOS for the Wii is NOT firmware. You can think of IOS files as "system files" which are stored on a "system on a chip" or SOC within the Wii. The Wii's SOC is called Starlet. Here's what you really need to know about IOS - the system files that it stores are the codes that the Wii uses to communicate with the Wiimotes, nunchuks, balance board, USB Instruments, DVD Drive, Gamecube Controllers, etc. Many IOS versions co-exist, since different games potentially need different IOS features. For instance, when Rock Band first shipped, it included an update that installed IOS37. IOS37 had some codes built into it that the Wii uses to control the USB Microphone for that game. It is important to understand that there are many IOS versions sitting on your Wii side-by-side. They do not overwrite each other and there are codes on the different games that tie to IOS versions.


Question 3: Neato - so what's the big deal with cIOS? Why do I need it?

Some smooth coders got together at some point and figured out how to patch and modify the system IOS to unlock various features of the Wii that would not typically be available. The first widespread implementation of this technique was DVDX - whereby a standard DVD could be read by the Wii's DVD drive (typically the Wii's DVD drive can only read Wii and Gamecube games). Based on DVDX, the homebrew application MPlayer was able to read DVD movie discs, and the DVD was opened up as a storage medium for various homebrew applications. The first disc backup loaders were also borne out of this customized/patched IOS.


Question 4: Um, woah...how does the cIOS work with my Nintendo's stock IOS? Does it overwrite it?? OMG AM I GOING TO BRICK MY Wii?!?!

The short answer is no. Because many IOS's co-exist on the Wii, it is possible to grab a stock one, patch and modify it, and add it as a brand new IOS for use with homebrew applications that can use it. This is absolutely critical and it's a huge step that the coders found a way to do it. All customized IOS versions install as an IOS in the 200+ range. All stock system IOS's are in the 30-50 range. Installing cIOS is safe because it never modifies your original IOS, it just adds another one. You can also easily remove the cIOS without adversely affecting the stock functionality of the Wii. The only way to brick your Wii when messing with IOS is to delete or modify a standard system IOS such as IOS36 or IOS38. Stay away from the system ones!


Question 5: Whew! OK good, so what is IOS249 and how does it relate to IOS36 or IOS38?

There has been a lot of work done on updating and improving the cIOS. When the USB Loader started to get popular, Waninkoko had been releasing cIOS36rev_(version). cIOS36 is a customized IOS based on system IOS36. It installs as IOS249. Subsequently, most revisions and updates (despite what version of official Nintendo IOS they are based on) will install as IOS249. IOS249 is the IOS that enables most of the hardware hacking such as USB Hard Drive Loading and DVDX. When new games come through with additional patches/IOS requirements, the coders will release a new cIOS to be sure to include all of the patches that are included with that update. That is why suddenly we are looking at cIOS38_rev13 instead of cIOS36_rev13. For maximum compatibility, I would suggest getting the latest stable cIOS release. What constitutes stable? Well...you'll need to do your homework and read forums/release notes.



It's worth noting that we are at a point where the new releases of patched Nintendo IOS's will install as IOS249 (except for the IOS222 as explained below). If you have IOS249 installed, that should be your de facto IOS for homebrew and other Wii hacks. An updated cIOS249 (whether from cIOS36_rev[version], cIOS38_rev[version] or beyond) is all you need. When a new one comes through, just download the new WAD file and use the WAD Manager to install it over the old cIOS249 (it will choose all of the correct settings for you...just install it). If you have a problem with a newer or buggy cIOS, then just grab an older version's WAD file and install it. It's that easy.


Question 6: So...what about uninstalling cIOS?

If you want to uninstall cIOS, all you need to do is use Any Title Deleter, or the WAD Manager (if you have the cIOS WAD that you used to install it originally) to delete IOS249. NEVER, EVER delete any IOS with a lower (2-digit) suffix. IOS30, IOS34, IOS36, IOS38, etc. should never be touched. If you remove one, you very well could brick your Wii.


Question 7: What the heck is IOS222

One current limitation of cIOS249 is that when you have a hard drive plugged into the Wii, the Wii doesn't like to accept a second USB device (such as a Rock Band microphone or a USB LAN Adapter ). I'm sure eventually this will be solved in cIOS249, but should you not want to wait, you can install cIOS222 by coder Hermes. This specialized cIOS was developed specifically to attempt a fix for the second USB port use issue. The USB Loader GX actually lets you choose whether you'd like to use cIOS222 or cIOS249 to load games. Generally you'll want to use cIOS249, but if you're in need of a Rock Band or USB LAN Adapter fix, you can load with cIOS222.