Introduction to Operating Systems

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Questions and Answers

What is the primary function of an operating system in a computer system?

To increase the speed of the CPU

To manage hardware and software resources (correct)

To enhance internet connectivity

To provide storage space on hard drives

Which of the following is NOT a major function of an operating system?

User Interface Design (correct)

Network Management

Process Management

Memory Management

Which component is responsible for managing the processes in an operating system?

Storage Controller

Process Scheduler (correct)

File System Manager

Memory Allocator

What does memory management in an operating system involve?

Allocating and deallocating memory space as needed Signup and view all the answers

How does an operating system provide security to a computer system?

By implementing user authentication and permissions Signup and view all the answers

What is one of the main goals of an operating system?

Make the computer system convenient to use Signup and view all the answers

Which component is responsible for managing hardware utilization?

Operating System Signup and view all the answers

How does an operating system act as a resource allocator?

It decides between conflicting requests for efficient resource use Signup and view all the answers

Which statement is true regarding how users perceive operating systems?

They want convenience and ease of use Signup and view all the answers

What role does an operating system play in the prevention of errors?

It controls execution of programs to prevent errors Signup and view all the answers

What is a characteristic feature of dedicated systems?

Users have dedicated resources but may share from servers Signup and view all the answers

What does the term 'kernel' refer to in operating systems?

The one program running at all times on the computer Signup and view all the answers

How is the performance of handheld computers typically optimized?

For battery life and usability Signup and view all the answers

What is NOT a typical component of a computer system?

Cloud Storage Signup and view all the answers

What describes users in the context of computer systems?

Entities utilizing the system resources Signup and view all the answers

What does increased reliability in computing systems typically ensure?

Graceful degradation or fault tolerance Signup and view all the answers

Which type of multiprocessing involves multiple nodes monitoring each other?

Symmetric Multiprocessing Signup and view all the answers

In a clustered system, what role does the storage-area network (SAN) play?

It provides shared storage across multiple systems. Signup and view all the answers

What is the primary goal of multiprogramming in an operating system?

To maximize CPU usage Signup and view all the answers

What is the expected response time for a timesharing system?

Less than 1 second Signup and view all the answers

What happens during the transition from user mode to kernel mode?

Only privileged instructions can be executed. Signup and view all the answers

What mechanism prevents a process from hogging system resources indefinitely?

Timer interrupts Signup and view all the answers

In which scenario would swapping occur?

When processes do not fit in memory. Signup and view all the answers

Which characteristic is NOT associated with symmetric clustering?

One machine in hot-standby mode Signup and view all the answers

What is considered a proactive measure by operating systems against software errors?

Exception or trap management Signup and view all the answers

What is the main purpose of the dual-mode operation in operating systems?

To protect the OS and system components. Signup and view all the answers

Which of the following best describes a process in a computing context?

A program in execution. Signup and view all the answers

When designing applications for high-performance computing (HPC) in clustered systems, what must be considered?

Implementation of parallelization. Signup and view all the answers

What is the primary role of the operating system in process management?

To create and manage user and system processes Signup and view all the answers

What does a single-threaded process use to track the next instruction?

One program counter Signup and view all the answers

What is NOT a responsibility of memory management in an OS?

Managing network connections Signup and view all the answers

What mechanism does the OS provide to prevent deadlocks between processes?

Synchronization mechanisms Signup and view all the answers

How does an OS typically organize files for user access?

Into directories Signup and view all the answers

Which of the following describes the role of the I/O subsystem in an OS?

Oversees the interaction between software and hardware devices Signup and view all the answers

Which storage type typically has slower access speeds but is used for long-term data retention?

Tertiary storage Signup and view all the answers

Which of the following identifies the main purpose of storage management in an OS?

To provide a uniform view of information storage Signup and view all the answers

What is the primary function of protection mechanisms in an OS?

To control access to resources Signup and view all the answers

What does the process of spooling in the I/O subsystem refer to?

Overlapping output from one job with the input of another Signup and view all the answers

What is the function of cache coherency in a multiprocessor environment?

To ensure all CPUs have the most recent value cached Signup and view all the answers

What is the significance of reclaiming resources during process termination?

To free up memory for other processes Signup and view all the answers

Which concept defines the potential for multiple processes to execute concurrently on a system?

Concurrency through multiplexing Signup and view all the answers

What does the bootstrap program do during computer startup?

It initializes all aspects of the system. Signup and view all the answers

What is a key function of an interrupt in an operating system?

To transfer control to the interrupt service routine. Signup and view all the answers

In the context of I/O operations, what does a wait instruction do?

It halts the CPU until the next interrupt is received. Signup and view all the answers

What purpose does the device-status table serve in an operating system?

It shows the current operational status of I/O devices. Signup and view all the answers

How does a device controller communicate the completion of an operation to the CPU?

By causing an interrupt. Signup and view all the answers

What defines a trap in operating systems?

A user-generated request causing a software interrupt. Signup and view all the answers

What is the main advantage of Direct Memory Access (DMA) in I/O operations?

It transfers data blocks directly to memory without CPU intervention. Signup and view all the answers

Which statement accurately describes the characteristics of main memory?

It is volatile and accessed randomly by the CPU. Signup and view all the answers

What principle underlies the function of caching in computer systems?

Copying frequently used data to faster storage temporarily. Signup and view all the answers

Why are interrupts disabled during the processing of another interrupt?

To avoid lost interrupts. Signup and view all the answers

Which characteristic does NOT apply to secondary storage?

It is typically accessible by the CPU directly. Signup and view all the answers

What is the role of a multiprocessor system?

To allow multiple CPUs to work on different tasks simultaneously. Signup and view all the answers

How does the storage hierarchy organize different types of storage?

Based on their volatility, speed, and cost. Signup and view all the answers

What is involved in the cache management process?

Determining cache size and replacement policy. Signup and view all the answers

Study Notes

What is an Operating System?

An operating system acts as an intermediary between a user and the computer hardware.
The goals of an operating system are:
- Execute user programs and make solving user problems easier.
- Make the computer system convenient to use.
- Use the computer hardware efficiently.

Computer System Structure

A computer system is composed of four components:
- Hardware: Provides basic computing resources (CPU, memory, I/O devices).
- Operating System: Controls and coordinates the use of hardware amongst applications and users.
- Application Programs: Define how system resources are used to solve user computing problems (word processors, compilers, web browsers, etc.).
- Users: People, machines, or other computers interacting with the system.

Operating System Functions

Depends on the perspective:
- Users prioritize convenience and ease of use, not resource utilization.
- Shared computer systems need to satisfy all users.
- Dedicated systems (e.g., workstations) have dedicated resources but often use shared resources from servers.
- Handheld computers prioritize usability and battery life due to limited resources.
Resource Allocator: Manages all resources and decides between conflicting requests for fair and efficient resource use.
Control Program: Controls program execution to prevent errors and improper use of the computer.

Kernel in Operating System

The kernel is the core of the operating system, always running.
Everything else is either a system program (shipped with the OS) or an application program.

Computer Startup

The bootstrap program, stored in ROM or EPROM (firmware), initializes the system at power-up or reboot.
It loads and starts the execution of the operating system kernel.

Computer System Organization

Components connect through a common bus:
- One or more CPUs.
- Device controllers.
- Shared memory.
Concurrent execution of CPUs and devices compete for memory cycles.

Interrupt Handling

Each device controller manages a specific device type and has a local buffer.
CPU transfers data between main memory and local buffers.
I/O happens between the device and the controller's local buffer.
The device controller informs the CPU of completion through an interrupt.

Interrupt Architecture

An interrupt transfers control to the interrupt service routine, typically through an interrupt vector that stores addresses of service routines.
The interrupt architecture saves the address of the interrupted instruction.
Incoming interrupts are disabled during interrupt processing to prevent loss.
A trap, a software-generated interrupt, is triggered by errors or user requests.
Operating systems are interrupt-driven.

I/O Structure

Wait Instruction: The CPU idles until I/O completion, preventing simultaneous I/O processing.
System Call: User requests the operating system to wait for I/O completion, allowing the CPU to continue processing other tasks.
Device-Status Table: Contains information about each I/O device, including type, address, and state.

Direct Memory Access (DMA)

Used for high-speed I/O devices that can transmit data at close to memory speeds.
The device controller transfers data directly between buffer storage and main memory without CPU intervention.

Storage Structure

Main Memory: Volatile memory that the CPU directly accesses. Offers random access.
Secondary Storage: Nonvolatile storage with larger capacity, extends main memory.
Magnetic Disks: Rigid platters covered with magnetic recording material. Surface is logically divided into tracks and sectors.

Storage Hierarchy

Storage systems are organized based on speed, cost, and volatility.
Caching: Copying information into a faster storage system temporarily.
- Main memory can act as a cache for secondary storage.

Computer-System Architecture

Most systems use a single general-purpose processor, but many have special-purpose processors.
Multiprocessor Systems: (parallel or tightly-coupled systems)
- Advantages:
  - Increased throughput.
  - Economy of scale.
  - Increased reliability (graceful degradation or fault tolerance).
- Types:
  - Asymmetric Multiprocessing: One processor is designated as the master, while others are slaves.
  - Symmetric Multiprocessing: All processors are equal and can run any task.

Clustered Systems

Multiple systems (nodes) working together, often sharing storage via a storage-area network (SAN).
Types:
- Asymmetric Clustering: One node in hot-standby mode.
- Symmetric Clustering: Multiple nodes run applications and monitor each other.
Used for high-availability service, surviving failures.
Some clusters focus on high-performance computing (HPC).

Operating-System Structure

Multiprogramming: Improves efficiency by organizing jobs (code and data), keeping the CPU busy.
- Subset of jobs is kept in memory.
- Job scheduling selects and runs a job.
- When waiting (e.g., for I/O), the OS switches to another job.
Timesharing (multitasking): CPU switches jobs frequently, enabling interactive computing.
- Each user has at least one program running in memory (a process).
- CPU scheduling manages multiple processes ready to run simultaneously.
- Swapping moves processes in and out of memory when they don't fit.
- Virtual memory allows execution of processes not fully loaded in memory.

Operating-System Operations

Interrupts: Triggered by hardware, software errors (exceptions/traps), or process problems (infinite loops, modifications).
Dual-Mode Operation: Protects the OS and other system components.
- User Mode: Used for user programs.
- Kernel Mode: Used for OS code.
- Mode Bit: A hardware mechanism to differentiate between modes, only allowing privileged instructions in kernel mode.
- System Call: Switches from user mode to kernel mode.

Timer Interrupt Handling

Prevents processes from hogging resources.
Timer interrupt is set after a specific period.
The OS decrements the timer counter.
At zero, the timer interrupt triggers, allowing the OS to regain control or terminate exceeding processes.

Process Management

A process is an active entity within a system that requires resources to execute.
A process includes a program, CPU, memory, I/O, files, initialization data and more.

Process Management Activities

An OS is responsible for creating and deleting both user and system processes, managing process synchronization and communication, and handling deadlocks.

Memory Management

Memory management is the art of optimizing CPU utilization and computer response to users by determining what is in memory when.
Memory management activities include:
- Tracking what parts of memory are in use and by whom.
- Deciding which processes and data to move in and out of memory.
- Allocating and deallocating memory space as needed.

Storage Management

The OS provides a uniform logical view of information storage by abstracting physical properties to logical storage units (files).
Files are usually organized into directories and can be accessed by authorized users.

Mass-Storage Management

Mass-storage management is important for data that does not fit in main memory or data that needs to be kept for a long time.
Disks are usually utilised for this data and proper management of this system is critical for computer speed.
Mass-storage management activities include free-space management, storage allocation and disk scheduling, including tertiary storage.

I/O Subsystem

The I/O subsystem is responsible for memory management of I/O, including buffering, caching, spooling and general device-driver interface.

Protection and Security

Protection refers to mechanisms for controlling access of processes or users to specific resources defined by the OS.
System security is the defense of the system against internal and external attacks, including denial-of-service, worms, viruses, identity theft, and theft of service.
User identities (user IDs, security IDs) include a name and an associated number, one per user.
User IDs are associated with files and processes to control access.

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Description

This quiz covers the basic concepts related to operating systems, including their functions, structure, and the components of a computer system. It highlights the role of operating systems as intermediaries between users and hardware, and how they enhance usability and efficiency.