i have drill and slot rotors with no markings on them. can anybody tell me witch way they go on?

 

Slots point forward

 

Keep in mind that you are trying to push air & dust out and away from the hub.

So when u install the disc, spin it and imagine it pushing air & dust AWAY from the hub, so as the disc spins (in the forward direction) the groove non-contact with the brake pad starts nearest the hub and finishes the furthest point from the hub