虚拟存储器的作用是允许(4)，它通常使用(5)作为主要组成部分。虚拟存储器的调度方法与(6)基本类似，即把经常要访问的数据驻留在高速存储器中。因为使用了虚拟存储器，指令执行时(7)。在虚拟存储系统中常使用相联存储器进行管理，它是(8)寻址的。

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Packet switching is a method of slicing(71) messages into parcels called "packets," sending the packets along different communication(72) as they become available, and then reassembling the packets(73) they arrive at their destination. Prior to the development of packet switching, early computer networks used leased, dedicated telephone circuits to(74) with terminals and other computers. In circuit-switched networks such as the telephone system, a complete point-to-point(75) is put together, and then communication can proceed.

URL consists of three parts: the protocol(75), the DNS name of the host (www.csai.cn) and the file name (index.html).

The essence of(74) is the invention of a hierarchical, domain-based naming scheme. It is primarily used for mapping host names and e-mail destinations to IP addresses.

As one of Gigabit Ethernet, 1000Base-Tuses(73) pairs of UTP.

To reduce their design complexity, most networks are organized as a stack of(72), each one built upon the one below it.

(71) are privately-owned networks within a single building or campus of up to a few kilometers in size.