Wayne asked: . Of course the real question is why you would want to format good 800k disks as 400k. I'm curious!" I'm more concerned with being able to read a 400k 3.5 disk than with format or write with it. The reason is that some older versions of very useful software comes for install on 400k 3.5 disks. Thus, the need to hope the SuperDrive can at least read them. Cheers, Tom