The standard IDE interface on the Amiga was the original design to handle hard drives alone; the SCSI interface started the same way (hard drive only), but was modified to handle non-hard drive devices. The ATAPI interface came along for the IDE controllers to handle optical drives, tape drives and such and is based on the developed SCSI commands. IDEFix software adds these ATAPI commands and one needs the addition of the Optical drive file system to interpret what is read, such as ASIMware's of other CDFS. There is more information out there on the web and some of it may actually be correct!