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