Apparatus and method for bus signal termination compensation during detected quiet cycle

A value to better match a termination circuit to a characteristic impedance of a bus signal line is determined. A determination is also made as to when a bus, that includes the line and that is being used by a bus agent in its normal mode of operation, will be available for adjusting the termination circuit in a Quiet Cycle, based at least on knowledge of the bus protocol and tracking of certain bus protocol events. The termination circuit is adjusted according to the determined value, during the Quiet Cycle.