Number of subscript which is attached to every element in array is classified as
Answer: B
Correct answer: number of dimensions
The number of subscripts each element takes is the number of dimensions: one for a list, two for a table, three for a block.
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Each entry in a segment table has a :
Answer: A
Correct answer: segment base
Each segment table entry holds the base - where the segment begins in physical memory - and the limit, its length.
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Modems are configured in such a manner that any incoming calls are automatically answered. Manufacturer provides inbuilt modems in many user computers. In this case the greatest security risk when dealing with the modems is
Answer: B
Correct answer: Remote access without the knowledge of network administrator
A modem set to answer automatically gives anyone who dials it a way into the machine, and through it into the network, that bypasses the firewall and every other perimeter control. Because it is inside the network and unrecorded, the administrator has no way of knowing the door exists.
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When variable used in program is whole number, variable is stored as
Answer: A
Correct answer: integers
A variable that will only ever hold whole numbers is stored as an integer, which uses less space than a real and is exact.
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The working set of a process is
Answer: A
Correct answer: the set of pages it has referenced in a recent interval
The working set is the set of pages a process has referenced within the most recent window of \( \Delta \) references. It is Denning’s model, and it is an approximation of the process’s current locality. Its purpose is practical. If every process is given enough frames to hold its working set, page faults stay rare and the system runs efficiently; if a process has fewer, it thrashes. The operating system therefore sums the working set sizes of all processes and, if the total exceeds the available frames, suspends one - freeing its frames for the rest rather than letting every process thrash together. The choice of window matters. Too small a \( \Delta \) misses part of the locality; too large a one spans several localities and overstates the requirement. Tracking it exactly is expensive, so it is approximated with reference bits sampled at intervals. The related control is page-fault frequency, which adjusts allocation by watching the fault rate directly rather than by measuring the working set.
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Every address generated by the CPU is divided into two parts :
Answer: B
Correct answer: page number & page offset
A logical address splits into a page number, which selects an entry in the page table, and a page offset, which is carried through unchanged to index within the frame.
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In fixed sized partition, the degree of multi programming is bounded by ___________
Answer: A
Correct answer: the number of partitions
One process per partition means the number of processes that can be in memory at once, and so the degree of multiprogramming, cannot exceed the number of partitions.
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Consider a computer with 8 Mbytes of main memory and a 128 K cache. The cache block size is 4 K. It uses a direct mapping scheme for cache management. How many different main memory blocks can map onto a given physical cache block ?
Answer: C
Correct answer: 64
There are \( 8\ \text{MB}/4\ \text{KB} = 2048 \) main memory blocks and \( 128\ \text{KB}/4\ \text{KB} = 32 \) cache lines. With direct mapping each line is shared by
\[ \frac{2048}{32} = 64 \]
different memory blocks, so any two of those 64 compete for the same line.
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When there is range of numbers involved in a program, it can be stored as
Answer: A
Correct answer: real numbers
A quantity that may take any value across a range, rather than only whole values, is stored as a real.
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A special quantity named in a program and its value can be changed is called
Answer: A
Correct answer: variables
A named quantity whose value may change during the run is a variable; one whose value is fixed is a constant.
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