Operating System (OS)
System maintenance:

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

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Operating System (OS)
Most of the microcomputer's operating systems like Apple DOS, MS DOS and PC DOS etc. are called disk operating systems because

they are memory resident
they are initially stored on disk
they are partly in primary memory and partly on disk
None of these
they are available on magnetic tapes

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Operating System (OS)
The LRU algorithm

pages out pages that have not been used recently
pages out pages that have been least used recently
None of these
pages out pages that have been used recently
pages out the first page in a given area

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