One of the tape guide rollers, roller R6 is coupled to an optical tachometer encoder disk 80 which generates signal patterns in relation to {HEAD ~ actual tape velocity} in {TAIL ~ the forward 26 and reverse 28 tape directions} 
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One of the tape guide rollers , roller R6 is coupled to an optical tachometer encoder disk 80 which generates signal patterns in relation to { HEAD ~ actual tape velocity } in { TAIL ~ the forward 26 and reverse 28 tape directions }
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 REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL