AL-501 Operating Systems - Dec 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDescribe the main functions of an operating system in managing hardware and software resources.
   How to answer

   • Define operating system as resource manager
   • List functions: process, memory, file, device, protection/security
   • Explain hardware management vs software/resource abstraction
   • Give examples of each function
2. 7 Marks
   bDefine System calls. Discuss the challenges associated with low-level implementation and portability issues of system calls.
   How to answer

   • Define system call as OS service interface
   • List types/examples
   • Explain low-level implementation challenges
   • Explain portability issues
3. 7 Marks
   aExplain the organization of hard disk and the steps involved in disk formatting and file system creation.
   How to answer

   • Describe hard disk physical/logical organization: platters, tracks, sectors, partitions
   • Explain low-level vs high-level formatting steps
   • Explain file system creation: mounting, structures
   • Diagram of disk layout
4. 7 Marks
   bAnswer the following:

   1. i)What challenges might arise in contiguous allocation of file storage?
   2. ii)A system uses contiguous allocation for files on a disk with 1000 blocks. If a file requires 200 blocks starting from block 10, calculate the ending block number.
   How to answer

   • Define contiguous allocation
   • List challenges: external fragmentation, file growth, pre-allocation
   • Calculate ending block = start + length -1 = 209
   • State assumption of 0/1 based numbering
5. 7 Marks
   aDefine a process and explain its different states with the help of a process state diagram.
   How to answer

   • Define process vs program
   • List states: new, ready, running, waiting, terminated
   • Draw process state diagram with transitions
   • Explain each transition
6. 7 Marks
   bAnswer the following:

   1. i)Discuss the scheduling challenges in a multiprocessor system.
   2. ii)A system uses Round-Robin scheduling with a time quantum of $5\ ms$. If three processes arrive simultaneously with burst times of $10\ ms$, $20\ ms$ and $30\ ms$, calculate the completion time for each process.
   How to answer

   • List multiprocessor scheduling challenges: affinity, load balancing, synchronization
   • Explain Round-Robin with time quantum 5 ms
   • Compute Gantt / completion times for burst 10, 20, 30 ms
   • State completion time of each process
7. 7 Marks
   aDescribe the concept of paging and how it helps in memory management. If a process requires 4 pages with a page size of 1 kB each, calculate the total memory required.
   How to answer

   • Define paging: fixed-size pages/frames, page table
   • Explain address translation and role in memory management
   • Calculate total memory = 4 pages x 1 kB = 4 kB
   • Mention reduced external fragmentation
8. 7 Marks
   bDefine Virtual Memory. Discuss its importance in modern operating systems.
   How to answer

   • Define virtual memory as illusion of large memory
   • Explain demand paging, swapping
   • Discuss importance: multiprogramming, larger programs, protection
   • Give examples
9. 7 Marks
   aDifferentiate between synchronous and asynchronous I/O operations.
   How to answer

   • Define synchronous I/O: blocking, process waits
   • Define asynchronous I/O: non-blocking, callback
   • Compare on basis of CPU utilization, complexity, examples
   • Tabulate differences
10. 7 Marks
    bExplain the role of the Kernel I/O Subsystem in an operating system. Discuss how I/O requests are transformed into hardware operations.
    How to answer

    • Define Kernel I/O subsystem services: scheduling, buffering, caching, spooling
    • Explain I/O request lifecycle: system call to driver
    • Explain transformation to hardware commands/interrupts
    • Mention performance and protection role
11. 7 Marks
    aAnswer the following:

    1. i)What are the desirable characteristics of a modern operating system?
    2. ii)A system is designed to handle 10 processes in a Round-Robin scheduling with a time quantum of $4\ ms$. Calculate the time taken for a single cycle if all processes require execution for $20\ ms$ each.
    How to answer

    • List desirable characteristics: efficiency, reliability, portability, security
    • Explain Round-Robin single cycle = 10 x 4 ms = 40 ms
    • Explain total execution need 20 ms each over multiple cycles
    • Conclude cycle time vs total time
12. 7 Marks
    bDescribe the concept of file protection and access control in operating systems.
    How to answer

    • Define file protection and access control
    • Explain access matrix, ACLs, permissions
    • Discuss importance for security and sharing
    • Give Unix permission example
13. 7 Marks
    aDefine Deadlock and explain the necessary conditions for a deadlock to occur.
    How to answer

    • Define deadlock
    • List four Coffman conditions: mutual exclusion, hold and wait, no preemption, circular wait
    • Explain each condition with example
    • State necessity of all four
14. 7 Marks
    bExplain how memory management is implemented in Unix/Linux operating systems.
    How to answer

    • Outline Unix/Linux memory model: paging, segmentation
    • Explain virtual memory, swap, page replacement
    • Explain kernel vs user address space
    • Mention buddy/slab allocators
15. 7 Marks
    aDefine dynamic linking and loading. Why is it useful in virtual memory systems?
    How to answer

    • Define dynamic linking vs static linking
    • Define dynamic loading
    • Explain benefits: memory saving, sharing, efficiency
    • Explain relevance to virtual memory/demand paging
16. 7 Marks
    bDefine Virtualization and its applications in operating systems.
    How to answer

    • Define virtualization: hypervisor, VMs
    • Explain types: hardware, OS-level, para-virtualization
    • List applications: server consolidation, isolation, testing
    • Mention benefits in OS context