a communication system having first and second states for use with a shared transmission line composed of at least two conductors and composed of first and second transmission line segments connected to each other at a single connection point . in the first state , a termination is coupled to the single connection point and is operative to at least attenuate a signal propagated between the first and second segments . in the second state , a driver is coupled to the connection point and is operative to conduct a signal over the first and second segments .