Abstract: A single-chip integrated circuit is disclosed, wherein the single-chip integrated circuit comprises at least one unidirectional communication channel for converting a first electrical signal to a first optical signal and at least one bidirectional communication channel for converting a second electrical signal to a second optical signal and converting a third optical signal to a third electrical signal.

Abstract: A switch control circuit is provided in a dual speed stackable networking device for automatically bypassing a faulty exchanging unit and monitoring the voltages of the associated input end and output end to prevent the occurrence of a traffic loop. When a number of dual-speed hubs are arranged in a stack, the output end of the current switch control circuit is coupled to the input end of a switch control circuit of next adjacent dual-speed hub. On the other hand, the output end of the current switch control circuit is coupled to the input end of a switch control circuit of another adjacent dual-speed hub. The switch control circuit includes a detector for detecting the power status of the exchanging unit, a logic unit for controlling the voltages of the input end and the output end. If the exchanging unit is not functioning normally, and the voltage of the output end is set to 0, then the exchanging unit is disabled by the switch control circuit.

Abstract: A network hub which allows the transmission of data at varying data transfer rates. Data is divided into different transfer protocols and converted by an exchange unit to transform the data of different groups into appropriate speed networks.