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6. Define the main idea of each paragraph. Text 27 Operating systems

In the world there are a lot of network operating systems. Among the most successful system are Unix, Novell Net Ware, Windows NT Server. All these system can restrict the rights of customers' file servers to allocate resources of the workstations. Each of these systems meets the criteria of safety, reliability and most importantly-security.

In addition to the system which primary function is to organize a file server, there are systems that provide the user on the network. These operating systems include Novell DOS, Windows for Workgroups, Windows 95-98, Windows NT Workstation. And the last operating system contains a tool to allow access to local networks, and the utilities access the Internet.

Currently most operating systems support a variety of networking protocols, hardware, and application for using them. That means that computers running dissimilar operating systems can participate in a common network for sharing resources such as computing, files, printers, and scanners using either wired or wireless connections. Networks can essentially allow a computer operating system to access the resources of a remote computer to support the same functions as it could if those resources were connected directly to the local computer. This includes everything from simple communication, to using networked file systems or even sharing another computer graphics or sound hardware. Some networks services allow the resources of a computer to be accessed transparently, such as SSH which allows networked users direct access to the computer command line interface.

Client/server networking involves a programm on a computer somewhere which connects via a network to another computer, called a server. Servers, ussually running UNIX or LINUX, offer various services to other network computers and users.

These services are usually provided through ports or numbered access points beyond the server network address. Each port number is usually associated with maximum of one running program, which is responsible for handling requests to that port. A domain, being a user program, can in turn have access to the local hardware resources of that computer by passing requests to the operating system kernel.

Many operating systems support one or more vendor-specific or open networking protocols as well, for example, SNA on IBM system, DECnet on system from Digital Equipment Corporation, and Microsoft-specific protocols (SMB) on Windows. Specific protocols for specific tasks may also be supported such as NFS for file access. Protocols like ESound, or ESD can be easily extended over the network to provide sound from local applications, on a remote system sound hardware.

1. Define the main idea of each paragraph.

2. Find the sentence expressing the main idea in each paragraph.