how it works: (quoted from Atlas forum) "DCC (Digital Command Control) operates on a square wave alterating current signal divided into a units called packets. The packet consists of a header (a signal to tell the decoder that this is the start of the packet), the body (basically the command), and a trailing set of bits at the end of the packet. Each time the voltage goes from 0 to + back past 0 to - and back to 0 is called a bit. The decoder basically ignores the trailing bits of the packet (there is no information there, just AC current) " Power for the DC motor is rectified from the track AC voltage. Presumably the header also includes the loco address, since multiple locos can be operated simultaneously.