A dual-screen user device and methods for revealing a combination of desktops on single and multiple screens are disclosed. A controlling apparatus determines a power supply mode of the Ethernet power sourcing equipment, and determines high-power Ethernet powered device and low-power Ethernet powered device among the Ethernet powered devices. Accessibility to either stringed musical instrument may be accomplished by neck portion rotation, relative to the body portion, facilitated by an ergonomically placed and designed handle assembly. The control unit detects a degree of response delay in reference to dispersion in a clock signal so as to perform response delay recovering and reduce dispersion of the response delay. A signal for processing the data is transmitted from the first device to the second device, through use of the second interface function, in a case where it is detected that the second device has the first interface function.