Paging and Segmentation

Question 1

What is a logical address?

Answer 1

The address generated by the CPU when a program is running.
It represents a location in the computer’s memory that the program wants to access.

Question 2

What is a physical address?

Answer 2

A physical address is the actual location in the computer’s memory hardware (RAM) where data is stored.

Question 3

What is paging?

Answer 3

A memory management scheme where we partition memory into small equal fixed-size chunks and divide each process into the same size chunks

Question 4

The chunks of a process are called

Answer 4

pages

Question 5

the chunks of memory are called

Answer 5

frames

Question 6

For each process there is a page table

Answer 6

True

Question 7

Formula for physical address

Answer 7

(frame*page size)+offset

Question 8

Where is the page table kept?

Answer 8

In main memory

Question 9

What is the PTBR?

Answer 9

Page table base register points to the page table

Question 10

What indicates the size of the page table?

Answer 10

Page table length register

Question 11

What is a TLB?

Answer 11

a memory cache that stores the recent translations of virtual memory to physical memory.

Question 12

What is effective access time?

Answer 12

The total time it takes to access data from a system

Question 13

EAT Formula

Answer 13

EAT=h(c+m)+(1-h)*(c+2m)
h=hit ratio
c=TLB access time
m=memory access time

Question 14

What is a hit ratio?

Answer 14

percentage of times that a page number is found in the associative registers: related to the number of associative registers

Question 15

What is Multilevel paging?

Answer 15

A paging scheme which consists of two or more levels of page tables in a hierarchical manner

Question 16

What are the three ways Address binding can happen?

Answer 16

Compile Time
Load Time
Execution Time

Question 17

What is a cache?

Answer 17

A high-speed storage mechanism that stores copies of frequently accessed or recently used data or instructions.

Question 18

Name two differences between logical and physical addresses

Answer 18

1. Tangibility: Logical addresses are virtual addresses that exist only within the program’s perspective, while physical addresses are real addresses that correspond to actual locations in physical memory.
2. Visibility: Logical addresses are visible to the programmer and are used in the program’s code, while physical addresses are hidden from the programmer and managed by the operating system’s memory management unit (MMU).

Question 19

What is contiguous allocation/ Simple paging?

Answer 19

a memory allocation method where data is stored in adjacent, continuous blocks of memory without fragmentation or physical gaps between them.

Question 20

What is fixed partitioning?

Answer 20

divide memory into a fixed number of partitions of equal or different size. This can be efficient for programs that have a predictable memory usage.

Question 21

What is dynamic partitioning?

Answer 21

divide memory into partitions of variable size. This can be more efficient for programs that have a variable memory usage.

Question 22

What is fragmentation?

Answer 22

a problem that occurs when memory is allocated in a way that leaves unused gaps between allocated blocks. This can make it difficult to allocate memory for new processes.

Question 23

Explain the difference between internal and external fragmentation.

Answer 23

Internal fragmentation:
Occurs when allocated memory is larger than needed, leaving unused space within the allocated block.

External fragmentation: Wastage of memory when there are enough total free memory spaces, but they are not contiguous or usable together.

Question 24

What is thrashing?

Answer 24

Thrashing occurs when processes are actively using more memory than is physically present. This causes a state of continuous paging;

Question 25

What is pre paging?

Answer 25

Prepaging, also known as anticipatory paging, involves loading not only the required page but also additional pages into memory preemptively before they are needed by a process.

Question 26

What is demand paging?

Answer 26

Demand paging is a memory management scheme that loads only the required pages into memory when a process initially starts execution.

Question 27

What is a page fault?

Answer 27

An interrupt that occurs when a program requests data that is not currently in real memory.