Question 1

Cache memory is based on the concept of using a large,fast,and expensive memory to supplement the workings of main memory.

Accepted Answer

Cache memory is indeed faster and more expensive per byte than main memory, but it is typically much smaller, not larger, in size. Its purpose is to speed up access to frequently used data and instructions by storing them closer to the CPU.

Question 2

With segmented memory allocation,each job is divided into several segments of the same size,one for each module containing pieces that perform related functions.

Accepted Answer

In segmented memory allocation, each job is divided into segments of different sizes, not necessarily the same size, based on the logical divisions of the program, such as modules or functions, rather than a fixed size.

Question 3

In a demand paging scheme,the first-in first-out (FIFO)page replacement policy chooses the page least recently accessed to be swapped out.

Accepted Answer

In a demand paging scheme, the FIFO page replacement policy chooses the page that has been in memory the longest, not the one least recently accessed, to be swapped out.

Question 4

The optimal selection of cache size and replacement algorithm can result in 80 to 90 percent of all requests being in the cache.

Accepted Answer

The optimal selection of cache size and replacement algorithm can result in a high cache hit rate, typically between 80 to 90 percent of all requests being satisfied by the cache.

Question 5

The key to the successful implementation of demand paging is the use of a high-speed CPU.

Accepted Answer

While a high-speed CPU may improve the performance of demand paging, it is not the key to successful implementation. Other factors such as efficient memory management and algorithms, adequate RAM, and optimized storage systems are also important.

Question 6

Thrashing is a problem that occurs when there are a large number of jobs and many free pages so that pages are being moved around too much.

Accepted Answer

Thrashing occurs when there are not enough free pages and the system is constantly moving pages in and out of memory, causing performance to decrease.

Question 7

A variation of the LRU page replacement algorithm known as the clock page replacement policy is implemented using a pointer to step through the reference bits of the active pages,simulating a clockwise motion.

Accepted Answer

The statement describes the clock page replacement policy, which uses a pointer to step through the reference bits of active pages in a circular manner, simulating a clock's motion.

Question 8

Virtual memory can be implemented with both paging and segmentation.

Accepted Answer

Virtual memory can be implemented using either paging or segmentation or a combination of both techniques.

Question 9

The primary advantage of storing programs in noncontiguous page frames (in a paged memory allocation scheme)is that main memory is used more efficiently because an empty page frame can be used by any page of any job.

Accepted Answer

Storing programs in noncontiguous page frames allows for better utilization of main memory, as empty page frames can be allocated to any page of any job, leading to a more efficient use of available space.

Question 10

With demand paging,if there are no empty page frames available,to move in a new page,one of the current resident pages must be placed into main memory.

Accepted Answer

With demand paging, if there are no empty page frames available, one of the current resident pages must be swapped out to disk (not placed into main memory) to make room for the new page.

Question 11

The segmented/demand paged memory allocation scheme is a combination of segmentation and demand paging,and it offers the logical benefits of segmentation,as well as the physical benefits of paging.

Accepted Answer

The given statement about the segmented/demand paged memory allocation scheme is true. It combines the advantages of segmentation and demand paging to provide logical and physical memory management benefits.

Question 12

Paged memory allocation offers the advantage that it doesn't require the entire job to be stored in memory during its execution.

Accepted Answer

The answer of Paged memory allocation offers the advantage that...

Question 13

When using a FIFO scheme,adding more memory always results in better performance.

Accepted Answer

While adding more memory can improve performance in many cases by reducing the number of page faults, it does not always result in better performance due to the Belady's anomaly, where increasing the number of page frames can lead to an increase in the number of page faults under certain conditions, particularly in a FIFO (First In, First Out) page replacement scheme.

Question 14

Demand paging introduced the concept of loading only a part of the program into memory for processing

Accepted Answer

Demand paging is a memory management technique where pages are loaded only when they are required by the process being executed. This reduces the amount of memory needed to store a program in memory and allows for more efficient use of memory resources.

Question 15

The Job Table (JT)contains two values for each active job: the size of the job and the memory location where its Page Map Table is stored.

Accepted Answer

The statement is true. The Job Table contains the size of the job and the memory location where its Page Map Table is stored.

Question 16

Associative memory is a name given to several hardware registers that are allocated to each active job whose task is to associate segment and page numbers belonging to the job being processed with their main memory addresses.

Accepted Answer

This statement is true. Associative memory is indeed a hardware register allocated to each active job in order to associate segment and page numbers with their corresponding memory addresses.

Question 17

With demand paging,three additional fields are introduced for each page in each PMT: one to determine if the page being requested is already in memory,a second to determine if the page contents have been modified while in memory,and a third to determine if the page has been referenced most recently.

Accepted Answer

This statement is true as demand paging requires three additional fields in each page's PMT to determine if the page is in memory, if the page contents have been modified and if the page has been referenced recently.

Question 18

In the bit-shifting variation of the LRU page replacement policy,the process of shifting bits to the right and resetting the leftmost bit to 1 when a page is referenced gives a history of each page's usage.

Accepted Answer

The process of bit-shifting and resetting the leftmost bit to 1 when a page is referenced is known as the "aging" or "clock" algorithm. This algorithm gives a history of each page's usage by maintaining a counter for each page that increments when it is referenced and periodically shifts the bits to the right. The leftmost bit acts as a reference bit that indicates whether the page has been referenced recently. Therefore, the statement in the question is true.

Question 19

In a paged memory allocation scheme,to find the actual position of an instruction in memory,first the page number and displacement are determined.Then the operating system refers to the job's PMT to correlate the page with its page frame.

Accepted Answer

This is the correct process for finding the actual position of an instruction in a paged memory allocation scheme. The page number and displacement are used to locate the page, which is then matched with its corresponding page frame using the job's page map table (PMT).

Question 20

A job's working set is the collection of pages that must be loaded from secondary storage.

Accepted Answer

The answer of A job's working set is the collection...

Quiz 3: Memory Management Includes Virtual Memory