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