The disk drive provides a non volatile backup for {HEAD ~ the random access memory} by transferring data between {TAIL ~ the disk drive} and random access memory automatically, or by command, on a non realtime basis 
The disk drive provides a non volatile backup for { HEAD ~ the random access memory } by transferring data between { TAIL ~ the disk drive } and random access memory automatically , or by command , on a non realtime basis
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH