As far as I know, the only 3.5 drive that works with the IIc is the UniDisk 3.5, and that's only if your IIc is upgraded. If your IIc is a model# A2S4000, and has a seriel # lower than F60516FA2S4000, it likely does not; if it's higher, and/or a A2S4100, it does for sure. I believe the IIc "smartport" will support up to 3 UniDisk 3.5s (I have two on mine) and 1 5.25 drive. -RPM