{HEAD ~ An electronic device} having electronic circuitry powered by a battery and having an interface for interactively coupling the electronic device to {TAIL ~ a host device}, for switching the power source by which power is supplied to the electronic circuitry, and by determining an interface status as being coupled to or detached from the host device 
{ HEAD ~ An electronic device } having electronic circuitry powered by a battery and having an interface for interactively coupling the electronic device to { TAIL ~ a host device } , for switching the power source by which power is supplied to the electronic circuitry , and by determining an interface status as being coupled to or detached from the host device
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