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An operating system acts as an intermediary between the user and the computer hardware.
An operating system acts as an intermediary between the user and the computer hardware.
True
The four main components of a computer system include hardware, application programs, users, and the operating system.
The four main components of a computer system include hardware, application programs, users, and the operating system.
True
Users of dedicated systems do not have access to shared resources from servers.
Users of dedicated systems do not have access to shared resources from servers.
False
The primary goal of an operating system is to maximize hardware resource utilization without considering user convenience.
The primary goal of an operating system is to maximize hardware resource utilization without considering user convenience.
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All computers have a universal user interface to interact with their operating system.
All computers have a universal user interface to interact with their operating system.
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An operating system is defined as the one program that runs at all times on a computer, known as the kernel.
An operating system is defined as the one program that runs at all times on a computer, known as the kernel.
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A mainframe computer must primarily focus on keeping one user happy.
A mainframe computer must primarily focus on keeping one user happy.
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Open-source operating systems are types of computing environments.
Open-source operating systems are types of computing environments.
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Protection and security is not a concern when designing an operating system.
Protection and security is not a concern when designing an operating system.
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The objective of operating systems includes making solving user problems easier.
The objective of operating systems includes making solving user problems easier.
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Virtualization is considered a slow method compared to using native code.
Virtualization is considered a slow method compared to using native code.
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A VMM, or Virtual Machine Manager, can operate only as a guest operating system.
A VMM, or Virtual Machine Manager, can operate only as a guest operating system.
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Cloud computing is a logical extension of virtualization.
Cloud computing is a logical extension of virtualization.
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A laptop running Mac OS X as a host can only run applications compatible with the Mac OS environment.
A laptop running Mac OS X as a host can only run applications compatible with the Mac OS environment.
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Interpreting a computer language means compiling it to native code.
Interpreting a computer language means compiling it to native code.
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Increased throughput can be achieved through economy of scale.
Increased throughput can be achieved through economy of scale.
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Asymmetric Multiprocessing has all processors performing the same task.
Asymmetric Multiprocessing has all processors performing the same task.
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Clustered systems typically share storage via a storage-area network.
Clustered systems typically share storage via a storage-area network.
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Symmetric clustering allows only one machine to run applications while others are idle.
Symmetric clustering allows only one machine to run applications while others are idle.
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Timesharing in operating systems requires response times greater than 1 second.
Timesharing in operating systems requires response times greater than 1 second.
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Multiprogramming allows multiple programs to occupy the memory for execution at the same time.
Multiprogramming allows multiple programs to occupy the memory for execution at the same time.
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A hardware interrupt can occur due to software errors.
A hardware interrupt can occur due to software errors.
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Virtual memory allows processes to execute even when they are not completely in memory.
Virtual memory allows processes to execute even when they are not completely in memory.
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In dual-mode operation, processes can run both in user mode and kernel mode without any restrictions.
In dual-mode operation, processes can run both in user mode and kernel mode without any restrictions.
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Multiprogramming organizes jobs so the CPU is always busy executing tasks.
Multiprogramming organizes jobs so the CPU is always busy executing tasks.
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A timer is used to prevent infinite loops by terminating programs that exceed their allotted time.
A timer is used to prevent infinite loops by terminating programs that exceed their allotted time.
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In client-server computing, dumb terminals are still the primary system used to respond to client requests.
In client-server computing, dumb terminals are still the primary system used to respond to client requests.
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All nodes in a peer-to-peer network must act exclusively as clients.
All nodes in a peer-to-peer network must act exclusively as clients.
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The TCP/IP protocol is commonly used for local area networking.
The TCP/IP protocol is commonly used for local area networking.
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Mobile computers utilize only wired connections for data networking.
Mobile computers utilize only wired connections for data networking.
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Traditional computing environments are defined by their lack of interconnectivity with other systems.
Traditional computing environments are defined by their lack of interconnectivity with other systems.
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Virtualization allows multiple operating systems to run applications within one another.
Virtualization allows multiple operating systems to run applications within one another.
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The main feature of distributed computing is the centralization of control in a single system.
The main feature of distributed computing is the centralization of control in a single system.
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Mobile devices typically include unique OS features such as GPS and gyroscopic sensors.
Mobile devices typically include unique OS features such as GPS and gyroscopic sensors.
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In a computing environment, the file-server system provides an interface for clients to request computational power.
In a computing environment, the file-server system provides an interface for clients to request computational power.
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Public clouds are designed exclusively for corporate use and are not available to the general public.
Public clouds are designed exclusively for corporate use and are not available to the general public.
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Real-time operating systems (RTOS) operate without any fixed time constraints.
Real-time operating systems (RTOS) operate without any fixed time constraints.
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Infrastructure as a Service (IaaS) includes applications that are available via the internet.
Infrastructure as a Service (IaaS) includes applications that are available via the internet.
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Hybrid clouds consist only of private cloud components.
Hybrid clouds consist only of private cloud components.
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The Free Software Foundation (FSF) initiated the project to develop open-source operating systems.
The Free Software Foundation (FSF) initiated the project to develop open-source operating systems.
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Load balancers are used to spread traffic across a single application.
Load balancers are used to spread traffic across a single application.
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GNU/Linux and BSD UNIX are examples of open-source operating systems.
GNU/Linux and BSD UNIX are examples of open-source operating systems.
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A bootstrap program is not necessary for computer startup.
A bootstrap program is not necessary for computer startup.
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In computer system operation, multiple CPUs can execute concurrently while competing for memory cycles.
In computer system operation, multiple CPUs can execute concurrently while competing for memory cycles.
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An interrupt is solely a hardware-generated signal.
An interrupt is solely a hardware-generated signal.
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Device controllers are responsible for managing multiple device types simultaneously.
Device controllers are responsible for managing multiple device types simultaneously.
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Main memory is the only nonvolatile storage medium directly accessible by the CPU.
Main memory is the only nonvolatile storage medium directly accessible by the CPU.
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Caching improves system performance by moving information from faster storage to slower storage.
Caching improves system performance by moving information from faster storage to slower storage.
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Direct Memory Access (DMA) allows high-speed I/O devices to transfer data without CPU intervention.
Direct Memory Access (DMA) allows high-speed I/O devices to transfer data without CPU intervention.
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Secondary storage is not volatile and can store large amounts of data.
Secondary storage is not volatile and can store large amounts of data.
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When an interrupt occurs, the address of the interrupted instruction is not saved.
When an interrupt occurs, the address of the interrupted instruction is not saved.
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The device-status table contains information about the state and type of each I/O device.
The device-status table contains information about the state and type of each I/O device.
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Operating systems primarily use polling rather than interrupts for device communication.
Operating systems primarily use polling rather than interrupts for device communication.
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Volatility is not a consideration when organizing storage systems into a hierarchy.
Volatility is not a consideration when organizing storage systems into a hierarchy.
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Solid-state disks are usually slower than traditional hard disks.
Solid-state disks are usually slower than traditional hard disks.
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Study Notes
Introduction
- Operating systems act as intermediaries between users and computer hardware.
- Key goals include executing user programs, ensuring user problem-solving ease, and efficient hardware use.
- The operating system's structure comprises hardware, operating system, application programs, and users.
- Computer systems are composed of interconnected hardware, the operating system, and application programs that work together to solve user problems.
- Users include people, machines and other computers.
Objectives
- Describe fundamental computer system organization.
- Detail major operating system components.
- Overview different computing environments.
- Investigate various open-source operating systems.
What is an Operating System?
- A program mediating user interaction with computer hardware.
- Operating system goals include easing user issues, making the system easy to use and efficiently using the hardware.
Computer System Structure
- Computer systems consist of four crucial components:
- Hardware (CPU, memory, and I/O devices).
- Operating system (controls hardware use and coordinates among various applications).
- Application programs (define methods to use system resources for tasks like word processing, compilation, web browsing, or database management).
- Users (people, machines, or other computers).
Four Components of a Computer System
- Users interact with the operating system to request services.
- The operating system manages the computer hardware's resources and makes them accessible to various programs and functions.
- System and application programs enable users to use the system.
- Computer hardware provides the basic computing resources.
What Operating Systems Do
- User needs influence operating system design.
- Shared computer systems (mainframes and minicomputers) demand balanced user satisfaction.
- Dedicated systems (workstations) feature dedicated resources but often share network and server resources.
- Specific computer types (handhelds) prioritize user interface simplicity and battery life.
- Embedded systems (like those in devices and automobiles) often lack an elaborate user interface.
Operating System Definition
- Operating systems are resource allocators.
- They manage all system resources.
- They prioritize conflicting requests to ensure system efficiency and fairness.
- Acting as a controller, it guides program execution to avoid errors.
Operating System Definition (Continued)
- No single, broadly accepted definition for operating systems exists.
- "Everything a vendor provides when you buy an operating system" is a common, yet not universal, approximation.
- "The single program that runs continuously" (the kernel), represents a another common approach, while everything else is either a system or application program.
Computer Startup
- The bootstrap program initiates the boot process.
- Typically stored in ROM or EPROM (often known as firmware), it initializes all system aspects.
- Then it loads the operating system kernel and starts its execution.
Computer System Organization
- Multiple CPUs and I/O device controllers connect through a system bus.
- This shared memory architecture allows concurrent CPU and device execution, though concurrent access to memory can lead to competing for the same resources and delays.
Computer-System Operation
- Inputs and outputs happen concurrently.
- Each device controller handles unique device types.
- CPUs move data between main memory and controller buffers.
- Device controllers notify the CPU when operations complete, using interrupts.
Common Functions of Interrupts
- Interrupts transfer control to interrupt service routines through an interrupt vector.
- Interrupt architecture saves the interrupted instruction address.
- A trap is a software interrupt (e.g., from a software error or user request).
- An operating system is largely interrupt-driven.
Interrupt Handling
- The operating system preserves important CPU states.
- Interrupt types are determined.
- Separate segments for each interrupt type determine the appropriate actions.
Interrupt Timeline
- Processes, I/O, or device interrupts can occur at any time leading to interruptions to the CPU's execution to respond to these events.
- The interrupt timeline shows the relationship between processes and I/O activities that might interrupt the main process.
I/O Structure
- Control returns to the user program only when I/O is finished.
- The CPU waits for an interrupt from the controller.
- I/O requests may be handled synchronously.
- The OS can handle an I/O request on behalf of the user.
- The operating system manages device I/O operations via a device status table, tracking device status.
Storage Structure
- Main memory is directly accessible by the CPU, typically volatile, and organized using random access or memory-mapped I/O.
- Secondary storage is for non-volatile storage extending main memory capacity.
- Hard drives use magnetic recording material on platters divided into tracks and sectors.
- Solid-state drives are faster and non-volatile and use various technologies.
Storage Hierarchy
- Storage systems are arranged in a hierarchical manner based on access speed and cost.
- Caching is used to copy information to faster storage mediums for efficiency.
- The operating system has device drivers to manage I/O operations for various controllers.
Storage-Device Hierarchy
- The diagram illustrates how storage devices are arranged hierarchically.
Caching
- Caching is a strategy to perform data access efficiently and temporarily store frequently accessed data in faster storage (cache) to improve retrieval speed compared to slower storage.
- The speed and cost of data access significantly affect whether caching effectively reduces delays.
- Cache management is critical in system design.
Direct Memory Access Structure
- High-speed I/O devices transfer data directly to memory.
- Device controllers directly handle data transfer without CPU intervention.
- Interrupts are generated only per memory block transfer, rather than per byte.
How a Modern Computer Works
- The diagram illustrates a modern computer's architecture using data flow and interrupts to show data transfer.
- A von Neumann architecture is used for modern computer systems.
Computer-System Architecture
- Most systems use one general-purpose processor, but some have specialized ones.
- Multiprocessor systems (parallel/tightly coupled) offer enhanced throughput, economy of scale, and fault tolerance.
- Multiprocessing types include symmetric (all processors execute all tasks) and asymmetric (specific tasks assigned to each processor).
Symmetric Multiprocessing Architecture
- A structure showing how multiple processors share resources and access memory.
A Dual-Core Design
- Systems with multiple processors on a single chip architecture.
Clustered Systems
- Similar to multiprocessors, but composed of multiple systems working together.
- Typically share storage via SANs.
- High availability is a key feature, with symmetric clusters offering redundancy and failure recovery through monitoring each other.
- HPC clusters are optimized for parallel computations.
Clustered Systems (continued)
- Systems are connected via storage-area networks (SANs) for efficient I/O.
Operating System Structure
- Multiprogramming (batch systems) use CPU time effectively for multiple unrelated tasks.
- Job scheduling and memory management are incorporated to ensure that one or more processes are always running on the CPU.
- Timesharing (multitasking) allows users to interact with multiple programs concurrently.
- Individual user interactions have a limited response time of typically under one second to give an interactive experience.
- Processes are loaded into memory in segments to allow execution without occupying all available physical memory, ensuring efficient use of the computer.
- Swapping moves processes between memory and disk when needed.
- Virtual memory extends the memory capacity beyond the system's physical memory limitations.
Memory Layout for Multiprogrammed System
- Example layout showing how multiple jobs and the operating system coexist in memory.
Operating-System Operations
- OSes are driven both by hardware and software interrupts.
- Hardware interrupts are triggered by various devices.
- Software interrupts (exceptions or traps) are triggered by software errors, operating system services, process problems (like infinite loops).
Operating-System Operations (Continued)
- Two modes of operation (user and kernel) exist to protect system components from harm; Mode bit is part of the hardware architecture to differentiate operating and user modes, allowing OS safeguards to be in place.
- Privileged instructions are crucial for OS operations in kernel mode, protecting from misuse.
- System calls are employed to transition from user mode to kernel mode.
- CPUs support multi-mode operations (like VM managers) to run multiple operating systems virtually.
Transition from User to Kernel Mode
- The operating system uses timers and scheduling mechanisms to prevent processes from monopolizing resources or running infinitely, guaranteeing user interaction; These timers assure processes don’t occupy the computer for longer than expected.
- System calls are used to transition from user mode to kernel mode.
Computing Environments - Traditional
- Stand-alone systems, increasingly networked.
- Web portals provide access to internal systems through the Internet.
- Thin clients (network computers) function as web terminals.
- Networking is now common and systems use firewalls for security.
Computing Environments - Mobile
- Portable devices like smartphones and tablets have operating systems.
- Features include GPS, gyroscopes, and augmented reality.
- Wireless or cellular connectivity is common (e.g. IEEE 802.11 Wi-Fi or cellular data networks).
Computing Environments - Distributed
- Separate systems, possibly heterogeneous, connect together in distributed computing.
- Communication paths include LANs (Local Area Networks), WANs (Wide Area Networks), MANs (Metropolitan Area Networks) and PANs (Personal Area Networks).
- Network Operating Systems manage inter-system communications.
- The goal is to provide an illusion of a single, unified system.
Computing Environments - Client-Server
- Dumb terminals are replaced with smart client devices like personal computers.
- Many systems offer services to clients (e.g., databases).
- Clients request services and interact with compute or file servers.
- Network servers manage client requests to provide access to network resources, services, and files.
Computing Environments - Peer-to-Peer
- All nodes are peers in this distributed architecture.
- Each participant can function as a client or server.
- Peer-to-peer networks use shared resources without centralized servers.
- Examples include Napster, Gnutella, and VoIP services.
Computing Environments - Virtualization
- OSes run applications within other OSes with various use cases, like compatibility and application development.
- Emulation is used when source and target CPU types differ.
- Often interpreted due to the necessary change in computer code or language.
- Virtual machine managers (VMMs) give flexibility to run multiple OSes on one computer with their own respective memory space.
- Guest VMs can run other OSes, applications, or systems software on top of the host OS and on its behalf.
Computing Environments - Cloud Computing
- Cloud computing provides on-demand access to computing, storage, or application resources.
- It's a logical extension of virtualization.
- Public cloud services are available via the internet (e.g. Amazon EC2 offerings).
- Various cloud types exist, such as private or hybrid clouds.
- The different services via the internet (e.g. Software as a Service, Platform as a Service, Infrastructure as a Service) provide various functions beyond just basic computing resources.
Computing Environments - Real-Time Embedded Systems
- Frequent in different computing environments, like those in devices or automobiles.
- Vary greatly in special use cases and often have limited-purpose operating systems or no operating system at all.
- Real-time operating systems handle tasks, and processing is crucial for the system to function as expected.
Open-Source Operating Systems
- Open-source OSs make the source code available, unlike closed-source ones.
- Counter to digital rights management (DRM) and copy protection.
- Free Software Foundation (FSF), using the GNU General Public License (GPL), promotes open-source software.
- Open-source OS examples include GNU/Linux, and others like BSD UNIX and core Mac OS X.
- Virtual machine managers (VMMs) like VirtualBox allow evaluation of other OSs on one host.
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Description
Test your knowledge on the key components, objectives, and functionalities of operating systems. This quiz covers various aspects of computer systems, including the role of the operating system as an intermediary and its impact on hardware resource utilization. Challenge yourself on the concepts and terminologies associated with operating systems.