The memory system 9, wherein the first time period is {TAIL ~ three time slots} and the second time period is {HEAD ~ three time slots} 
The memory system 9 , wherein the first time period is { TAIL ~ three time slots } and the second time period is { HEAD ~ three time slots }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD