Copy CDROM to ISO image file

1. Using dd
   [root] dd if=/dev/cdrom of=/usrISO/tncdcopy.iso

2. Using cat
   [root] cat /dev/cdrom > /tmp/trendnet.iso 

Note: 
1. Ensure that the cd-rom is not mounted
2. These two commands will produce the same result and same size of ISO image