I dug out my old Mac SE to start my Mac shrine. I thought it would be fun to put Dark Castle on it and I found some disk images in a ".2mg" format on the web.
However, I can't figure out how to convert these .2mg files into anything I can use.
According to the extension listing, a .2mg is an 800K image of an Apple IIgs floppy converted for use with a PC IIgs emulator. So, I guess this would be some software that you may not be able to use directly on your 'new' SE
