1. A terminal apparatus comprising: a microphone configured to detect an audio signal; a touch panel display configured to detect an external it; and circuitry configured to: store a plurality of application programs each having computer readable instructions, said plurality of application programs including a first application program and a second application program; execute instructions of the first application program; display a screen generated by the circuitry on the touch panel display when executing the first application program; store data on the first application program when an operation of the first application program is paused; and respond to the external input by changing the screen to a screen image of the second application program, said external input including a dragging operation of an external device on the touch panel display so as to pause the first application program, wherein in response to the circuitry receiving the external input, the circuitry causes image data generated for the first application program while being executed and data of an execution state of the first application program to be stored for subsequent retrieval when resuming execution of said first application program into the circuit, the circuitry simultaneously displays a partial screen image for the first application program with a partial screen image of the second application program prior to fully transitioning to a display of an entirety of the screen image for the second application program, the circuitry gradually increases a display area of the screen image for the second application program in accordance with the dragging operation, and the circuitry places the second application program into an execution state when the display area of the screen image for the second application program is more than a predetermined threshold ; wherein: said plurality of application programs have respective priorities assigned thereto, and in response to said external input, screen images for said plurality of application programs that are in one of a paused state and an execution state are displayed in priority order.