References:

http://ee.hawaii.edu/~tep/EE160/Book/chap1/subsection2.1.1.1.html#SECTION0011100000000000000

http://en.wikipedia.org/wiki/Personal_computer_hardware

http://en.wikipedia.org/wiki/Operating_system

http://www.ehow.com/list_5954327_parts-floppy-drive-_amp_-functions.html

http://www.thinkwiki.org/wiki/Error_Codes_and_Beep_Codes

http://www.computerhope.com/beep.htm

http://fcit.usf.edu/network/chap5/chap5.htm

http://www.ianswer4u.com/2011/05/ring-topology-advantages-and.html#ixzz2LF3qhSLc 

http://www.functionx.com/networking/index.htm