There is provided a magnetic recording medium including an MgO underlayer that can be formed by a mass production process and has a thickness of 3 nm or less as well as including a magnetic recording layer made of an L10-type FePt ordered alloy having excellent magnetic properties. The display module three-dimensionally displays an image in a first region of a display screen and displays information in a second region of the display screen, the display screen capable to switch two-dimensional display and three-dimensional display. A battery response voltage curve is calculated based on the voltage differences between the plurality of battery response voltage readings.