Ok so I need some help from my GBAtemp buddies. So I have a ton of mame roms on my pc and I transferred some over to Retroarch and none of them work (I had correct bios and file structure). I found a download of converted roms to run on Final burn alpha and they work great but are missing quite a few good ones like metal slug 3. My question is: Is there a good place to find converted roms or maybe a way to convert them myself? And why do thy have to be different?