The wording you used could be interpreted a few different ways... "Remember that the CF adapter is a IDE adapter!" Are you saying that the CF circuitry and pads on the I-Opener's MoBo are connected directly to the IDE bus? Because that's true... Or are you saying that CF in general is IDE...? Which is very untrue. CF is a sort of mix between PCMCIA _bus_ and IDE. It has two (more?) modes.
In the mode like PCMCIA, it can have any address available to the CF slot, just like an ISA, PCI, or PCMCIA card can have any address available to the respective busses. In this mode, the CF card MUST pick up an address and have registers set and load drivers. In this mode, any type of device can be in the CF card: RAM, network interface cards, serial ports, scsi adapters, whatever someone decides to make. The IO does not support this ability, I'm almost certain.
The other mode is transparent IDE mode, which I described above. This is the only mode that the IO can use, as far as I can tell. I don't see any way that it could be otherwise without a huge amount of specialized circuitry (and "card services" support in the OS, like for PCMCIA cards). One of the control pins on the CF card tells it to run in IDE mode. The layout and meanings of the pins change for this mode, and the card acts exactly like an IDE drive. IDE can't really be called a "bus" like we mean PCI, ISA, and PCMCIA "busses", since IDE drives don't occupy an address of the computer... They have only two "addresses": Master and Slave, and both master and slave always use the same port/address that the IDE controller uses (170h, or 1F0h, if I remember correctly). From what I've read of the CF spec, there is no possible way to use a non-storage (doesn't have an IDE mode!) card in the CF slot on the IO, or any IDE-CF adapter for that matter.
Sorry if I'm restating things that everyone already knows and are tired of hearing. I was just a bit confused about what Patrick said. I've read alot of the CF spec (can be downloaded free from the CF website, I don't know the URL off hand) and plan to use the IDE mode on my own projects...
Patrick, do you hotswap the CF card in your IO?(!) Of course, it's not _supposed_ to be hotswapped, and doesn't have the appropriate circuitry, but I was wondering if you'd seen what happens when you pull out and/or plug in a card while the computer's running. Some OS's with special software/drivers (drivers loaded and unloaded as modules?) might be able to handle this, but I'm afraid to try it. I noticed you use it for digital camera memory... I couldn't imagine rebooting Windows (and waiting for it to load) every time you wanted to change the CF card. The main use I can see of the CF slot is for a semi-removable, silent ;) bootable "hard disk" (how I use it), or to be used for a "picture frame" with some tiny OS which boots quickly. I saw that you use the IOs for MP3 players and such, do you use it as a picture frame in the car?