NC file extension for a Robotool mill

HI, Does anybody happen to know what the NC file extension is for a Robotool cnc mill with a Micro CNC 1000 controller? I have tried using .txt, .tap so far with no recognition from the controller. This controller uses the 3 1/2 inch floppy disk\'s and I am not sure if the disk\'s are the formatted type or un-formatted type either.
Thanks,
bruski

Just guessing, but most controllers I\'ve seen like .NC and .CNC or some such.

at work, our fadal is .fad & our tsugami is .tsu .  maybe try .rob?

Thanks for the suggestions, I will try them today and hope for the best.
bruski