Logic control circuitry 320 is connected to the first tracking bit line and usable to convert the voltage change on {TAIL ~ the first tracking bit line DBL} into {HEAD ~ the SAE signal} 
Logic control circuitry 320 is connected to the first tracking bit line and usable to convert the voltage change on { TAIL ~ the first tracking bit line DBL } into { HEAD ~ the SAE signal }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD