A method of operating a memory controller to control a memory device includes reading a read vector from the memory device and correcting one or more errors in the read vector, where a power consumed at the correcting is varied according to the number of errors in the read vector. The emergency light source is activated by an activator comprising at least one of a manual activator and at least one light detector detecting a predetermined reduction in ambient light, wherein the activator is operatively coupled to the energizing circuit and causes the energizing circuit to operatively couple the battery power source and the LEDs; . The method involves superfilling by rapid bottom-up deposition at a superfill speed by which Cu deposition in a vertical direction from the bottoms of the features to the top openings of the features is substantially greater than Cu deposition on the side walls.