The disks are divided into {TAIL ~ sectors} and each sector as a symbol marking {HEAD ~ printed thereon} 
The disks are divided into { TAIL ~ sectors } and each sector as a symbol marking { HEAD ~ printed thereon }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD