Introduction to Operating Systems Week 2 NPTEL Assignment Answers 2025

NPTEL Introduction to Operating Systems Week 2 Assignment Answers 2025

1. Match the following

    a. CR0      1)Remove free pages from the list
    b. CR3      2)Enable paging
    c. kalloc()     3) Page table point register
    d. kfree()      4) Add free pages to the list

• a-3, b-2, c-1, d-4
• a-2, b-3, c-1, d-4
• a-2, b-3, c-4, d-1
• a-3, b-2, c-4, d-1

Answer : See Answers 

2. Match the following

    a. First Instruction        1) Application Processor begins to boot
    b. Real mode            2) Frequency at which DRAM is flushed and set
    c. BIOS                 3) 16 Byte below the 1 MB region of the RAM
    d. Startup IPI          4) Backward compatible with 8088

• a-1, b-3, c-4, d-2
• a-2, b-1, c-4, d-3
• a-2, b-1, c-3, d-4
• a-3, b-4, c-2, d-1

Answer : See Answers 

3. State True or False

Protection bit indicates that a block corresponds to OS code or User code.

• True
• False

Answer : See Answers 

4. State True or False

Master Boot Record allows the user to select which OS need to loaded.

• True
• False

Answer : See Answers 

5. In a 32 bit processor the virtual address is 22 bit:12 bit(Table index : Offset). What is the size of the page frame and the process page table assuming that each entry in the page table is 4 Bytes?

• 4KB, 4MB
• 4MB, 8MB
• 4MB, 16KB
• 4KB, 16MB

Answer : See Answers 

6. The bootloader switches the OS from ______________ to ____________.

• Protected mode, real mode
• User mode, kernel mode
• User mode, protected mode
• Real mode, Protected mode.

Answer :  See Answers 

7. Match the following

    a. Single contiguous model  1) Scan through all the free blocks.
    b. Best Fit                 2) Program memory size is restricted to RAM size
    c. First Fit                3) Fragmentation is worsed
    d. Worst Fit                4) Allocates the largest free block.

• a-4, b-3, c-1, d-2
• a-2, b-1, c-4, d-3
• a-2, b-1, c-3, d-4
• a-3, b-1, c-4, d-2

Answer : See Answers

8. State True or False

walkpgdir function create the page directory entry but will not create the table.

• True
• False

Answer :

9. Let the number of bits required to address a memory word be 25. Each word is of 16 bits.

1. Number of words in the memory is ______________.
2. Number of bytes in the memory denoted as ____________.
3. Number of bits to address ______________.

Where W denotes word and B denotes bytes.

• 32 KW, 64 KW, 29
• 32 MW, 64 MB, 26
• 64 KW, 32 MW, 29
• 64 MW, 32 MB, 26

Answer :

10. The lgdt instruction is used to ____________

• Fills the segment descriptor in GDT.
• Fills the Data segment descriptor in the GDT.
• Fills the GDT in an MMU register.
• Fills the Kernel code segment in the GDT.

Answer :

11. Which one of the following is true?

• Block size is not equal to the frame size.
• Need to allocate frames into the blocks of the RAM.
• Every memory access has an additional overhead, which can be reduced by using a TLB.
• Per process page table is stored in hard disk.

Answer :

12. The number of bits for limit, segment base and type in a 32 bit segment descriptor is

• 20,32,2
• 32,20,2
• 32,20,4
• 20,32,4

Answer :

13. PTPR(Page Table Point Register) is known as ____________ register in Intel systems

• CR0
• CR1
• CR2
• CR3

Answer :

14. Consider a system using 2-level paging and the virtual address is 38 bits. The most significant 12 bit are used to index the page directory and next 14 bits index the page table. Each entry in both level is 4 Bytes.

        1. How large are the page frames ?
        2. Size of page tables?

• 4KB, 16KB
• 4B, 16KB
• 4KB, 64KB
• 4B, 32KB

Answer : See Answers