In a DVD video playback system adapted to transmit data in the form of a PS from a source device to each sink device, a navigation manager of the source device stores system parameters, which are necessary for each sink device to decode the PS, in an unused area of a NV_PACK received from a PS demultiplexer and transmits it to a PS multiplexer. The apparatus further includes a feedback circuit to program a gain of the sensor, wherein the feedback circuit is coupled to the optical detector and to the coil. A hollow space defined by the walls of the loop permits the case, with the flashlight enclosed, to be attached to a key chain, article of clothing, or other support. A signal received at the input port is routed through the holey fiber at an angle of incidence to achieve total internal reflection. The transport path is further defined by two pairs of transport rollers, one roller of each pair above the transport path and one roller of each pair below the transport path. The driver unit includes a display drive unit, a power supply unit and a control unit.