Accordingly, diode D1 is forward biased so that {HEAD ~ a low logic level signal} will have been applied to {TAIL ~ the first input} of NOR gate 130 
applied to
Accordingly , diode D1 is forward biased so that { HEAD ~ a low logic level signal } will have been applied to { TAIL ~ the first input } of NOR gate 130
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH