I am under the impression that tyranid does not read this forum... But anyway, if you try and convert an ISO and then run "fc -b oldiso.iso newiso.iso" in DOS, you'll find that the "conversion" only changes 1 byte of the file. It's normally 64 bytes into the start of the .ISO and its a letter (for example J changes to E ou U for european or american Saturn models)
The correct way to do it is to find the header, that begins with the "SEGASATURN" string. But I really don't have the documentation around here. Can anyone help?