Abstract: The control unit causes a heater to operate when a temperature of a supply air flow is equal to or lower than a first temperature threshold, the temperature of the supply air flow being measured by an outdoor air temperature sensor while an air supply blower and an exhaust blower are in operation and the heater is stopped; and controls a protective operation mode when a temperature of the supply air flow is equal to or lower than a second temperature threshold, the protective operation mode being a mode in which the air supply blower is intermittently operated or is stopped and the exhaust blower continues operation, the temperature of the supply air flow being measured by the outdoor air temperature sensor after the heater is caused to operate.

Abstract: The display screen displays measure windows corresponding to the first through fourth measures for a melody to be composed. By clicking the play switch on the screen, a background accompaniment performance covering the four measures is played back to indicate the beats in the progressing tempo, thereby representing the rhythm speed. In time to the accompaniment progression, the user inputs note time points by tapping the input switch such as a space key in the keyboard to constitute a rhythm pattern for a melody progression. The measure window has a time axis in the horizontal direction and a pitch axis in the vertical direction. The tap-inputted note time points are exhibited at the corresponding positions along the time axis from left to right. Each point is dragged with the mouse pointer upward or downward to an intended pitch level, thereby establishing a pitch thereof.

Abstract: A method of and a device using a testing sheet having magnetically recorded thereon a magnetic head deviation detection signal formed on a portion of a predetermined spiral magnetic track or on a portion of a predetermined spiral magnetic track and on at least one side of such one portion. By causing a magnetic head mounted on a turntable of magnetic recording and reproducing apparatus for magnetically recording and reproducing electric signals in a spiral track to move along the predetermined spiral track on the testing sheet which is fixed, it is possible to find out if the magnetic head is able to trace the predetermined spiral magnetic track without deviating therefrom.