The array substrate includes a substrate, a thin film transistor and a pixel electrode. The interface circuit is operable to interface the memory circuits and the system for emulating at least one memory circuit with at least one aspect that is different from at least one aspect of at least one of the plurality of memory circuits. The method also includes performing a subsequent adjustment of power in response to the direction of change in the subsequent average impedance, wherein the subsequent adjustment of power is reverse to that of the first adjustment of power when the direction of change in the first and subsequent average impedances is the same.