The output of the latch 14 also is fed back for {TAIL ~ input} to {HEAD ~ the adder} 12 
The output of the latch 14 also is fed back for { TAIL ~ input } to { HEAD ~ the adder } 12
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH