Abstract: A heat assisted magnetic recording head is provided, which can prevent an effect of a heat in a laser diode when a magnetic recording region is heated by a heating laser beam and which can reduce its size and weight. In the heat assisted magnetic recording head, a recording magnetic pole, a magnetic recording element, a magnetic read element, an optical waveguide, and an irradiating optical waveguide are attached to a floating slider provided below a suspension. The laser diode is arranged on an opposite side of the suspension to the floating slider. The heating laser beam emitted from the laser diode is directed to the irradiating optical waveguide through the optical waveguide, so that a magnetic recording medium is irradiated with the heating laser beam exiting from the irradiating optical waveguide.

Abstract: A controller includes a first memory of non-volatile that stores a program; a processor that executes the program; and a second memory that provides a work area for the processor. In this controller, the processor executes the program read from the first memory and stored in the second memory as a first mode, and executes the program stored in the first memory as a second mode.

Abstract: In a non-insulated DC—DC converter for performing direct-current power conversion by operating a first MOS transistor and a second MOS transistor in mutually inverted phases, the second MOS transistor is held off during soft-start control. In soft-start control, the on-duty period of the first MOS transistor is short immediately after the switch-on of a power source, and is gradually extended afterwards.