CY-404 Operating Systems - Jun 2023 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
   aDiscuss the functions of operating system.
   How to answer

   • Define operating system as resource manager and extended machine
   • List functions: process, memory, file, device, security management
   • Explain each function briefly with examples
   • Mention user interface and system call interface role
2. 7 Marks
   bList and explain the types of system calls.
   How to answer

   • Define system call as interface between process and OS
   • List types: process control, file management, device management, information maintenance, communication
   • Explain each type with examples like fork, open, read, wait
   • Diagram of system call execution if needed
3. 7 Marks
   aDiscuss the characteristics of operating system.
   How to answer

   • Define operating system characteristics
   • Discuss concurrency, sharing, long-term storage, efficiency
   • Explain batch, multiprogramming, time-sharing features
   • Mention reliability and portability
4. 7 Marks
   bWrite and explain the process states with a neat sketch.
   How to answer

   • List five states: new, ready, running, waiting/blocked, terminated
   • Provide neat process state transition diagram
   • Explain transitions: admit, dispatch, interrupt, I/O wait, exit
   • Explain role of scheduler in transitions
5. 7 Marks
   aDefine semaphore. How does the semaphore work. Illustrate with an example.
   How to answer

   • Define semaphore as integer synchronization variable
   • Explain wait/P and signal/V operations with queue
   • Distinguish counting vs binary semaphore
   • Illustrate with producer-consumer or mutual exclusion example
6. 7 Marks
   bList the conditions that must be present for deadlock to occur and for each condition give brief example or reason that illustrate the disadvantage in preventing the condition.
   How to answer

   • List four Coffman conditions: mutual exclusion, hold and wait, no preemption, circular wait
   • Give brief example for each condition
   • Explain why preventing each condition is disadvantageous/costly
   • Conclude deadlock requires all four simultaneously
7. 7 Marks
   aDifferentiate between internal and external fragmentation.
   How to answer

   • Define fragmentation in memory allocation
   • Explain internal fragmentation: wasted space inside fixed partition
   • Explain external fragmentation: scattered free holes
   • Compare in table: cause, location, solution like compaction/paging
8. 7 Marks
   bExplain the procedure that ensure protection using paging.
   How to answer

   • Explain paging address translation with page table
   • Describe valid-invalid bits and protection bits
   • Explain how illegal access traps via page table entry
   • Mention TLB and read/write/execute permissions
9. 7 Marks
   aWrite short notes on memory management in UNIX.
   How to answer

   • Outline UNIX memory management: paging and swapping
   • Explain text, data, stack regions and page replacement
   • Mention buddy system / slab or free list
   • Note demand paging and virtual memory support
10. 7 Marks
    bSuppose the head of a moving head disk with 200 tracks, numbered 0 to 199, is currently serving a request at track 143 and has just finished a request at track 125. If the queue of requests is kept in FIFO order: 86, 147, 91, 177, 94, 150, 102, 175, and 130 What is the total head movement to satisfy these requests for the FCFS disk scheduling algorithms?
    How to answer

    • State FCFS services requests in FIFO order from current head at 143
    • Compute absolute differences: |143-86|+|86-147|+... etc.
    • Sum to get total head movement in tracks/cylinders
    • State final total = 565 tracks
11. 7 Marks
    aDiscuss in brief the following diskspace allocation method: Linked
    How to answer

    • Define linked allocation with directory pointer to first block
    • Explain each block contains pointer to next block
    • List advantages: no external fragmentation, dynamic size
    • List disadvantages: sequential access, pointer overhead, reliability
12. 7 Marks
    bDiscuss in brief the following diskspace allocation method: Indexed
    How to answer

    • Define indexed allocation with index block
    • Explain directory holds pointer to index block with block pointers
    • List advantages: direct access, no external fragmentation
    • List disadvantages: index overhead, size limit
13. 7 Marks
    aExplain in detail about asynchronous operations in I/O management.
    How to answer

    • Define synchronous vs asynchronous I/O
    • Explain non-blocking, overlapped computation and I/O
    • Describe device drivers, interrupts, buffers in async operation
    • Give examples of async system calls
14. 7 Marks
    bList out the differences between distributed and multiprocessor operating systems.
    How to answer

    • Define distributed vs multiprocessor OS
    • Compare on memory, communication, coupling, autonomy
    • Tabulate differences: shared memory vs message passing
    • Give examples of each system
15. 14 Marks
    Write short notes on any two of the following:

    1. a)Utility programs
    2. b)Virtual concurrency
    3. c)Paged segmentation
    4. d)File Systems in UNIX
    How to answer

    • Select any two topics from a-d
    • Define each topic with key features
    • Explain working with diagram/example where applicable
    • Conclude with advantages/applications