Conduct Internet research to review at least three contemporary operating systems (OS). Select at least one Mac and one Windows OS, along with one of the following OS types: (a) *NIX family OS, (b) a mainframe OS, (c) an embedded OS, or (d) a real-time OS. What do you believe is the role of an OS in contemporary computer systems? How does that role vary for different kinds of computers? Explain your answer. Be sure to cite the resources you used to support your findings.