Ok I believe Demul does run .dat files but I don't have any experience on how to do that..Do you have a full MAME set that is fairly recent? If so you can check out my .bat file from the download section on the forum if you place the .bats in your MAME ROMs directory and run them and it will create a folder with copies of all the Naomi, Sammy Atomiswave, Hikaru, Gaelco and Cave games along with a bios folder just move the copied folders into Demul and point Demul to them in the settings and they will all work except Cave there is a bios file missing I think if I point the program to my MAME ROMs also then the Cave games run so I'm missing something and haven't bothered to track it down yet. There are a ton of posts where I have screen shots of the Demul command lines in them if you can't find them let me know and I'll post them again.