Paging concept and page tables in Operating Systems - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the size of a page in bytes.

Operating Systems

page_size = 2[1]12  # Page size is 2 to the power of 12 bytes

Drag options to blanks, or click blank then click option'

A*

B**

C//

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' instead of '**' for exponentiation.

Using '//' which is integer division.

Using '+' which adds numbers instead of exponentiation.

The page size is calculated as 2 raised to the power of 12, which equals 4096 bytes. The '**' operator is used for exponentiation in Python.

2fill in blank

medium

Complete the code to calculate the number of pages given the total memory size.

Operating Systems

num_pages = total_memory_size [1] page_size

Drag options to blanks, or click blank then click option'

A//

B*

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' which multiplies instead of dividing.

Using '+' or '-' which do not calculate pages correctly.

Integer division '//' is used to find how many whole pages fit into the total memory size.

3fill in blank

hard

Fix the error in the code to correctly access the frame number from a page table entry.

Operating Systems

frame_number = page_table[page_number][1] 12

Drag options to blanks, or click blank then click option'

A>>

B-

C+

D<<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<<' which shifts bits left, increasing the number.

Using '+' or '-' which do not manipulate bits.

The '>>' operator shifts bits to the right, which is used here to get the frame number by removing the offset bits (12 bits for page size 4096).

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps page numbers to frame numbers for pages with even frame numbers.

Operating Systems

page_frame_map = {page: page_table[page] [1] 12 for page in range(num_pages) if (page_table[page] [2] 12) % 2 == 0}

Drag options to blanks, or click blank then click option'

A>>

B<<

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<<' which shifts bits left incorrectly.

Using '+' or '-' which do not perform bit shifts.

Both blanks use the right shift operator '>>' to extract the frame number by shifting 12 bits to the right.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps page numbers to frame numbers only if the frame number is greater than 1000.

Operating Systems

filtered_map = { [1] : page_table[[2]] [3] 12 for [2] in range(num_pages) if (page_table[[2]] [3] 12) > 1000 }

Drag options to blanks, or click blank then click option'

Apage

Bpage_number

C>>

D<<

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Using '<<' instead of '>>' for bit shifting.

The dictionary maps each page to its frame number by right shifting 12 bits. The variable 'page' is used consistently for clarity.