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