Operating System (OS)
System maintenance:

always requires several programs
is not required if the system is well written
is usually not necessary
None of these
is necessary on all systems, regardless of how good

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Operating System (OS)
Virtual Memory

consists of those addresses that may be generated by a processor during execution of a computation.
None of these
is a method of allocating processor time.
is a method of memory allocation by which the program is subdivided into equal portions, or pages and core is subdivided into equal portions or blocks.
allows multiple programs to reside in separate areas of core at the time.

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