processor means for reading {HEAD ~ data} from {TAIL ~ said main memory means} and writing data into said main memory means 
from
processor means for reading { HEAD ~ data } from { TAIL ~ said main memory means } and writing data into said main memory means
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH