单项选择题
The purpose of
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is to enlarge the
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, the set of addresses a program can utilize. For example, it might contain twice as many addresses as main memory. A program using all of it, therefore, would not be able to fit in main memory all at once. Nevertheless, the computer could execute such a program by Copying into main memory those portions of the program needed at any given point during execution.
To facilitate copying
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into real memory, the operating system divides it into pages, each of which contains a fixed number of addresses. Each page is stored on a disk until ii is needed. When the page is needed, the operating system copies it from disk to main memory, translating the
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into real addresses. The process of translating virtual addresses into real addresses is called
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. The copying of virtual pages from disk to main memory is known as
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or swapping.
A．former addresses
B．fake address
C．virtual addresses
D．mendacious addresses
