notes17

notes17 - Introduction Virtual Memory is a a system that...

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Introduction Virtual Memory is a a system that allows the use of storage in hard drives, etc. as though they wer part of physical memory (RAM). The CPU uses a "Virtual Memory Address" while RAM uses a "Physical Memory Address." There is a device called an MMU that does the translation from Virtual Memory to Physical Addresses History Creator Virtual Memory was created by Peter Denning, a former faculty member of Purdue University. Purpose The purpose was to overcome the limitations of RAM size by storing parts of program not in use in disk. Uses Exceed Physical Constraint Virtual Memory allows running programs in machines where the memory requirements of programs exceed the total RAM. The OS will keep in RAM only the sections of the program that are in use. The other sections are on disk backed by either the executable file or "swap space." Performance Virtual memory speeds loading of programs by only loading currently need pages from disk. Rather than loading the entire binary when a program starts, pages are loaded on demand thus reducing startup time. Economizes RAM Only those portions of a program that are in use are kept in memory. This saves RAM. Protection
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notes17 - Introduction Virtual Memory is a a system that...

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