Its in essence a tape drive but you dont have to manually move tapes. That why you will have the motors inside. They move the tape around inside and the single slot in the front is normally called the mail slot. If you need to move a single tape in and out of the autoloader you put it in that slot and the robot arm inside picks it up and moves it to the correct location. Some of the larger ones have removable cartridges that you load 8-16 tapes a side.