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			          Operating Systems (Software) Facts, Information, Pictures - Encyclopedia.com
			           
			          A computer's operating system is one of the most important "parts" of the computer. Almost every type of computer-including mobile telephones, video game systems, E-book readers, and DVRs-needs an operating system in order to operate properly.
			            http://www.encyclopedia.com/topic/Operating_systems_(Software).aspx
			         
			       
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			          General-Purpose Operating System
			           
			          The operating system (OS) sets the standards for all application programs that run in the computer.
			            http://encyclopedia2.thefreedictionary.com/General-purpose%20operating%20system
			         
			       
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			          Understanding Operating Systems
			           
			          Computer Basics: Understanding Operating Systems
			            http://www.gcflearnfree.org/computerbasics/2/print
			         
			       
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			          Operating System Functions -  HowStuffWorks
			           
			          Operating System Functions - Operating system functions include managing the hardware and software in a device such as a computer or phone. Read about operating system functions.
			            http://computer.howstuffworks.com/operating-system2.htm
			         
			       
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			          Operating Systems - Introduction
			           
			          Operating Systems - Introduction to Information and Communication Technology
			            http://openbookproject.net/courses/intro2ict/system/os_intro.html
			         
			       
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			          How Your Operating System Works
			           
			          How your operating system works - It sits there quietly but what does it actually do under the hood?
			            http://www.techradar.com/us/news/software/operating-systems/how-your-operating-system-works-936273
			         
			       
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			          Pros, Cons and Costs of Computer Operating Systems
			           
			          "Fools rush in where angels fear to tread", said Alexander Pope. The Mac vs. Windows debate is a distinct case in point and usually generates more heat than light.
			            http://www.nashnetworks.ca/pros-cons-and-costs-of-operating-systems.htm
			         
			       
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			          How Operating Systems Work
			           
			          The operating system controls your computer's tasks and manages system resources to optimize performance. Learn how your operating system works.
			            http://computer.howstuffworks.com/operating-system.htm
			         
			       
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			          List of Operating Systems - Wikipedia, the free encyclopedia
			           
			          This is a list of operating systems. Computer operating systems can be categorized by technology, ownership, licensing, working state, usage, and by many other characteristics.
			            https://en.wikipedia.org/wiki/List_of_operating_systems
			         
			       
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			          Operating System - Wikipedia, the free encyclopedia
			           
			          An operating system is system software that manages computer hardware and software resources and provides common services for computer programs.
			            https://en.wikipedia.org/wiki/Operating_system