The system 1, wherein said detecting means includes {TAIL ~ level detector means} coupled to said connection terminal means for detecting a power supply from {HEAD ~ said external device} 
The system 1 , wherein said detecting means includes { TAIL ~ level detector means } coupled to said connection terminal means for detecting a power supply from { HEAD ~ said external device }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD