Abstract: One embodiment of the present invention provides a method for selectively multiplexing a plurality of signal lines through an I/O pin on a semiconductor chip. The method starts by initializing a transmitting circuit and a receiving circuit to selectively multiplex the plurality of signal lines from the transmitting circuit through the I/O pin and into the receiving circuit. This initialization process includes selecting at least one of the plurality of signal lines to be multiplexed through the I/O pin, as well as synchronizing the transmitting circuit and the receiving circuit by asserting a reset signal. Once the transmitting and receiving circuits are initialized, the selected signal lines are multiplexed from the transmitting circuit through the I/O pin and into corresponding memory elements in the receiving circuit. Note that the transmitting circuit and the receiving circuit are driven by a common clock signal.