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