Each FIFO buffer 710 a 710 d accepts {HEAD ~ every fourth or Mth count} for a total of {TAIL ~ N counts} 
Each FIFO buffer 710 a 710 d accepts { HEAD ~ every fourth or Mth count } for a total of { TAIL ~ N counts }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL