Then {HEAD ~ the system} reads the data in all the sectors of the disk with a reading routine, and saves {TAIL ~ the data} in the free memory space 
saves
Then { HEAD ~ the system } reads the data in all the sectors of the disk with a reading routine , and saves { TAIL ~ the data } in the free memory space
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH