Eric Rothfus has created a device which allows you to use disk images that you normally use with emulators for a virtual disk drive that you can now attach to the apple II computer.
This device all but eliminates the need for a disk drive and makes my apple IIplus a completely 100% solid state machine (no moving parts). The device is simple to use, simple load your image into the SVD using a serial cable connected to your PC running SVD software. With the SVD device connected to your Disk ][ controller as drive 0, simply turn on your Apple II and it will boot off the SVD. The Apple II does not know it is anything other than a Disk ][ drive.
No need to worry about diskettes and where to find them, you don't need them! This is hands down the 2nd best device I've seen for the Apple II since the CFFA compact flash card. As an avid Apple II user I can't speak highly enough about this device. Just to test it out further, I ran a .nib image on it to verify that it would work and it does! ADT can't do that!
The two drawbacks I ran into are no way to write to the SVD at this time. Eric had the same problem with the TRS-80's when he first developed the SVD and I'm sure he will get through this issue too. This means some software that wants to store saved games won't save or won't work. No write protect option. I'm going to look to hack the SVD but Wizardry won't work unless the source disk is write protected, so this would need to be fixed, minor issue.
Overall, I give this device a thumbs up must have for the Apple II user. For more information you can go to the SVD website here:
Hope this helps,