Introduction to Operating Systems Week 2 NPTEL Assignment Answers 2025
Need help with this week’s assignment? Get detailed and trusted solutions for Introduction to Operating Systems Week 1 NPTEL Assignment Answers. Our expert-curated answers help you solve your assignments faster while deepening your conceptual clarity.
✅ Subject: Introduction to Operating Systems
📅 Week: 1
🎯 Session: NPTEL 2025 July-October
🔗 Course Link: Click Here
🔍 Reliability: Verified and expert-reviewed answers
📌 Trusted By: 5000+ Students
For complete and in-depth solutions to all weekly assignments, check out 👉 NPTEL Introduction to Operating Systems Week 1 NPTEL Assignment Answers
🚀 Stay ahead in your NPTEL journey with fresh, updated solutions every week!
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 :
3. State True or False
Protection bit indicates that a block corresponds to OS code or User code.
- True
- False
Answer :
4. State True or False
Master Boot Record allows the user to select which OS need to loaded.
- True
- False
Answer :
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 :
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 :
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.
- Number of words in the memory is ______________.
- Number of bytes in the memory denoted as ____________.
- 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
NPTEL Introduction to Operating Systems Week 2 Assignment Answers 2024
1. In which of the following cases would a page fault occur?
i) When a requested address is not in RAM
ii) When a write operation is issued on a read-only page.
Options:
a) i only
b) ii only
c) i and ii only
d) neither i nor ii
Answer: c
Explanation: A page fault occurs when the requested page is not present in the main memory (RAM). This applies to both situations: when a page is absent (i), and when there’s an access violation like writing to a read-only page (ii). So both conditions can trigger a page fault.
2. A new process, Pnew of size 10k. According to the following allocations, Pnew will be placed in:
a) Best Fit – p4, p3, p6
b) First Fit – p4, p9, p6
c) Worst Fit – p5, p9, p7
d) Best Fit – p5, First Fit – p3, Worst Fit – p7
Answer: d
Explanation:
- Best Fit chooses the smallest available partition that fits the process.
- First Fit selects the first partition in memory that is big enough.
- Worst Fit picks the largest available partition.
Based on this, option (d) correctly maps Pnew to partitions for each fit strategy.
3. Match the following:
a) CR0
b) CR3
c) kalloc()
d) kfree()
- Remove free pages from the list
- Add free pages to the list
- Page table point register
- Enable paging
Options:
a-3, b-2, c-1, d-4
a-2, b-3, c-1, d-4
a-4, b-3, c-1, d-2
a-3, b-2, c-4, d-1
Answer: a-4, b-3, c-1, d-2
Explanation:
- CR0 controls system functions; it enables paging.
- CR3 holds the physical address of the page directory base, used for paging.
kalloc()removes a page from the free list to allocate it.kfree()adds a page back to the free list.
4. The code from MBR is copied to RAM at location 0x7cc0 by BIOS
Options:
a) True
b) False
Answer: b
Explanation: BIOS copies the MBR code to memory address 0x7C00, not 0x7CC0. Therefore, the statement is false.
5. _____________ performs the Power On Self Test.
Options:
a) BIOS
b) Bootloader
c) Kernel
d) None of the above
Answer: a
Explanation: The BIOS (Basic Input/Output System) performs POST (Power-On Self-Test) to check hardware components before handing over control to the bootloader.
6. Consider a system with total memory available is 2^64 bytes. A user writes a C program on this system that uses the entire address space. The size of a pointer defined in this C program should be ______ bytes.
Answer: 8
Explanation: A pointer must be able to address the full address space. Since 2^64 = 16 exabytes, a 64-bit (8 bytes) pointer is needed to address this space.
7. The space in hard disk used to store inactive pages of a process is called _____________.
Options:
a) /tmp folder
b) User’s home directory
c) Swap space
d) None of the above
Answer: c
Explanation: Swap space is used to hold pages that are not currently active in RAM. It extends virtual memory by using hard disk space.
8. The bootloader in an x86 system switches the OS to ______________ from ____________.
Options:
a) Protected mode, Real mode
b) User mode, kernel mode
c) User mode, protected mode
d) Real mode, Protected mode
Answer: a
Explanation: The system starts in Real mode (16-bit). The bootloader switches to Protected mode (32-bit or 64-bit) to allow advanced OS functions.
9. Match the Following:
a) Present bit
b) Dirty bit
c) Swap out
d) Swap in
- Difference in contents of page in RAM and the Disk
- Moving a page from Disk to RAM
- Moving a page from RAM to Disk
- Page is present in RAM
Options:
a-1, b-3, c-4, d-2
a-2, b-1, c-4, d-3
a-4, b-1, c-3, d-2
a-3, b-4, c-2, d-1
Answer: a-4, b-1, c-3, d-2
Explanation:
- Present bit = whether page is in RAM
- Dirty bit = indicates page in RAM is modified vs. Disk
- Swap out = move from RAM to Disk
- Swap in = move from Disk to RAM
