With the printing initiation instruction, the printer and {HEAD ~ the host computer} perform {TAIL ~ the two way communication} through the parallel communication I/O interfaces 
perform
With the printing initiation instruction , the printer and { HEAD ~ the host computer } perform { TAIL ~ the two way communication } through the parallel communication I / O interfaces
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH