Excuse me.... my memory might be faulty with this.
System 7 can read but not write to a Mac 400K disk in MFS on a 68030 Mac with a Super or HD Drive. This includes the SE\30, Mac SE with Super or HD Drive (even though it is not a 68030 Mac), and the Mac II series.
System 6 can read and most of the time write a 400K MFS disk but only off the drive is a 800K Drive and not the 1.4M Super or HD Drive. This improves when you are using Mac 512K, Mac Plus or Mac SE. Even a Mac II with 800K drives it will work most of th time.
I think it is something to do with the Super Drive and the SWIM. I just can't remember the exact reasons for it.
System 7 can read but not write to a Mac 400K disk in MFS on a 68030 Mac with a Super or HD Drive. This includes the SE\30, Mac SE with Super or HD Drive (even though it is not a 68030 Mac), and the Mac II series.
System 6 can read and most of the time write a 400K MFS disk but only off the drive is a 800K Drive and not the 1.4M Super or HD Drive. This improves when you are using Mac 512K, Mac Plus or Mac SE. Even a Mac II with 800K drives it will work most of th time.
I think it is something to do with the Super Drive and the SWIM. I just can't remember the exact reasons for it.