^ I don't know if it's the same, but I actually meant Central Processing Unit, which is the part of the computer that makes all the 'calculations' and gives orders.
The turntable can turn to the left as well as to the right. When the train leaves the station (always forward), he drives to the transfer table. If the majority voted forward, the transfer table turns to the right, so the train can run forward. In case they voted backward, he turns to the left.