a processing part configured to provide said signal input by said external input unit to said {TAIL ~ device} and configured to provide to said external output unit, in real time, a signal having a same contents as said signal being input by {HEAD ~ said external input unit}, wherein 
a processing part configured to provide said signal input by said external input unit to said { TAIL ~ device } and configured to provide to said external output unit , in real time , a signal having a same contents as said signal being input by { HEAD ~ said external input unit } , wherein
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH