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2006-01-14 13:31:04
这节主要介绍了单用户操作系统与多用户操作系统在结构上的差异（比如终端）。给我最大的感觉是站在用户的角度看OS与站在OS设计者的角度看OS，所考虑的问题是完全不同的，或者说，思维方式是有所差异的，临界资源的处理在并发系统中是极为关键的。
Distributed operating systems
Distributed systems consist of computers connected by a communications medium such as a local area network (LAN).
接下来讨论了服务器性能与网络带宽的问题。
Requirements of operating systems
l To support separate activities at the application level (external to the operating system)
l For separate activities within the operating system: it must handle simultaneous requests from a number of its clients and it must handle simultaneously active devices
l There is a need for some of the separate activities to cooperate to achieve a common goal
l There is a need to manage competition for resources by separate activities
l Separate activities must be able to read and write system data structures without interference
l There is a need for a single task to be carried out as a whole, even when it involves a number of related subtasks.
//没什么好记的
基于GUI的应用程序中，不同应用程序不同窗口之间的切换，同一应用程序内不同窗口的切换与使用，同样是并发要考虑的一种情况。
(C) icymoon@NKU
