> anyway, very small isssue, don't know if this was an intentional feature or if
> you just overlooked it

Yes, it was intentionally created like that but I didn't know that anyone used non-seperated BIOS sets. I hadn't actually noticed that CMPro had an option for it if I am completely honest! I might be able to add a switch to MAMEDiff so that it understands non-seperated BIOS ROMs (-b perhaps) but I'll have to think if there are any adverse consequences first. ;)