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