The client-server model is popular in distributed systems. Can it also be used in a single-computersystem?
操作系统的任务是为用户程序提供一个更好、更简单、更清晰的计算机模型，管理计算机硬件设备。
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Layering enables the engineers to integrate an enormous amount of complexity into a single, working computersystem.
分层使工程师能够将庞大数量的复杂性集成到一个单一的工作计算机系统中。
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Finally, a simpler form of virtualization is operating system virtualization, in which a singlecomputer runs numerous operating systems of the same type.