Disclosed herein are methods for determining the copy number of a chromosome in a fetus in the context of non-invasive prenatal diagnosis. A second power system supplies electric power to a load further on a downstream side than the second power system. The front side protect material is configured to become fluid during solder reflow. The keyboard mode control software module operates on the processor, and controls whether the processor converts the unique input signals from the letter keys into character codes or telephony tone signals.