CEST-CE Term_2 GNU/LINUX (Week 11 -2)
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Questions and Answers

What is the primary goal of a multiprogrammed system?

  • To allow for user interaction with computer programs
  • To ensure all jobs are executed simultaneously
  • To utilize various system resources effectively (correct)
  • To require long response times for each user

    • In time-sharing systems, how does the CPU manage multiple jobs?

  • By executing all jobs in parallel
  • By executing jobs one at a time
  • By switching among jobs frequently (correct)
  • By prioritizing jobs based on their size

    • What is a key characteristic of a time-shared operating system?

  • It requires extensive memory allocation for each user
  • It executes long-running jobs sequentially
  • It prevents multiple users from sharing the computer
  • It allows users to interact with programs directly (correct)

    • What technique may a time-sharing operating system use to maintain reasonable response times?

    <p>Swapping processes in and out of memory</p> Signup and view all the answers

    What impression do users have in a time-sharing system, despite sharing the computer?

    <p>They have exclusive access to all resources</p> Signup and view all the answers

    What does the term 'swapping' refer to in an operating system context?

    <p>Moving processes between main memory and disk</p> Signup and view all the answers

    Which device prevents user interaction in a multiprogrammed system?

    <p>Output device</p> Signup and view all the answers

    Which statement is NOT true regarding the characteristics of a time-sharing system?

    <p>It does not allow direct user communication with the system</p> Signup and view all the answers

    What is the primary advantage of using virtual memory in an operating system?

    <p>It enables programs larger than the actual physical memory to run.</p> Signup and view all the answers

    What causes a trap in an operating system?

    <p>A software error or specific request from a user program arises.</p> Signup and view all the answers

    Why is dual-mode operation necessary in an operating system?

    <p>To distinguish between operating-system code and user-defined code.</p> Signup and view all the answers

    What happens when an operating system detects an interrupt?

    <p>The operating system switches to kernel mode to handle the interrupt.</p> Signup and view all the answers

    What would most likely occur without error protection in an operating system?

    <p>Errors in one program could impact the execution of other programs.</p> Signup and view all the answers

    What is the effect of running an incorrect or malicious program in a single-process execution model?

    <p>It could lead to incorrect execution of the one process running.</p> Signup and view all the answers

    In what mode does the operating system have the highest level of control over system resources?

    <p>Kernel mode</p> Signup and view all the answers

    What does the virtual memory technique primarily abstract?

    <p>Main memory into a larger array of storage.</p> Signup and view all the answers

    What is the purpose of the mode bit in a computer's hardware?

    <p>To distinguish between kernel mode and user mode operations</p> Signup and view all the answers

    In which mode does the computer start during system boot time?

    <p>Kernel mode</p> Signup and view all the answers

    What happens when a user application requests a service from the operating system?

    <p>The system transitions from user mode to kernel mode</p> Signup and view all the answers

    What is the significance of privileged instructions in operating systems?

    <p>They are designated to prevent users from executing harmful operations</p> Signup and view all the answers

    What is one potential benefit of having multiple modes in a CPU beyond just kernel and user modes?

    <p>It facilitates virtualization and enhances management of virtual machines</p> Signup and view all the answers

    How does the dual mode of operation protect the operating system?

    <p>By allowing the operating system to enforce restrictions on harmful tasks</p> Signup and view all the answers

    When does the system switch from kernel mode back to user mode?

    <p>Before passing control to a user program</p> Signup and view all the answers

    What is the state of the mode bit when the operating system gains control of the computer?

    <p>It is set to 0</p> Signup and view all the answers

    What is the purpose of the timer in an operating system?

    <p>To ensure the operating system maintains control over the CPU</p> Signup and view all the answers

    How does the timer notify the operating system when a program has exceeded its allowed runtime?

    <p>By decrementing a set counter and generating an interrupt</p> Signup and view all the answers

    What happens when the timer's counter reaches zero?

    <p>The operating system is informed and takes control</p> Signup and view all the answers

    In the context of the operating system, what is a potential reason for using a fixed timer period?

    <p>To standardize the scheduling of CPU time for processes</p> Signup and view all the answers

    Which of the following statements about the Virtual Machine Monitor (VMM) is correct?

    <p>The VMM has more privileges than user processes but fewer than the kernel</p> Signup and view all the answers

    What is one method the operating system uses to prevent user programs from failing to release control?

    <p>Implementing a timer mechanism</p> Signup and view all the answers

    What is the primary role of an operating system?

    <p>To manage the computer's hardware</p> Signup and view all the answers

    How does a control program within an operating system function?

    <p>By managing the execution of user programs to prevent errors</p> Signup and view all the answers

    What is multiprogramming in the context of operating systems?

    <p>Keeping several jobs in memory simultaneously</p> Signup and view all the answers

    What is one of the responsibilities of an operating system from the computer's perspective?

    <p>Coordinating external device interactions</p> Signup and view all the answers

    When jobs are too numerous for main memory, where are they kept initially?

    <p>In a job pool on the disk</p> Signup and view all the answers

    What is a key benefit of multiprogramming for CPU utilization?

    <p>It ensures constant execution of at least one job</p> Signup and view all the answers

    From the user's point of view, what does the operating system primarily provide?

    <p>An interface to interact with the hardware</p> Signup and view all the answers

    What resource does an operating system control as part of its management duties?

    <p>The allocation of main memory</p> Signup and view all the answers

    Study Notes

    Operating Systems Overview

    • An operating system (OS) is a program that manages computer hardware and provides a foundation for application programs.
    • It serves as an intermediary between users and computer hardware.

    User and System Viewpoints

    • User View: The user's experience varies depending on the interface.
    • System View: The OS operates closely with hardware, acting as a resource allocator and manager.

    Multiprogramming

    • Multiprogramming allows multiple jobs to reside in memory simultaneously, enhancing CPU utilization.
    • Jobs are initially stored on disk in a job pool due to limited main memory.
    • The system executes one job at a time but can switch when a job is waiting for I/O operations.

    Time Sharing

    • Time-sharing is an advancement over multiprogramming, enabling multiple users to interact with programs simultaneously.
    • Each user gets the perception of dedicated access despite sharing system resources.
    • Interactive systems provide immediate feedback (e.g., via keyboard or mouse input).
    • Focus on reasonable response time is crucial, often managed through swapping or virtual memory techniques.

    Virtual Memory

    • Virtual memory allows processes to execute even if they are not fully loaded in physical memory.
    • It abstracts main memory into a large array of storage, providing a seamless user experience.

    Dual-Mode Operation

    • Operating systems operate in two modes: user mode and kernel mode to protect system integrity.
    • The mode bit indicates the current operation state: kernel (0) or user (1).
    • User applications operate in user mode, while system calls transition to kernel mode for execution.

    System Initialization and Control

    • Upon boot, a system starts in kernel mode, loading the OS and user applications in user mode.
    • Events like traps or interrupts trigger a switch from user mode to kernel mode.

    Protection Mechanisms

    • To safeguard the OS from erroneous user programs, specific machine instructions are privileged.
    • This dual-mode system protects against buggy applications and ensures shared resource stability.

    Timer Functionality

    • A timer prevents user programs from monopolizing CPU time by setting an interrupt after a specified duration.
    • The system initializes the timer to limit the execution time of user applications, ensuring system responsiveness.

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    Related Documents

    w11_2_OS Concepts.pdf

    Description

    This quiz explores the fundamental role of operating systems in managing computer hardware and as an intermediary for application programs. It highlights the user's perspective and the system's functionalities, helping to clarify the essential aspects of operating systems. Test your knowledge on how these systems operate and their significance in computing.

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