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Chapter 2
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What is the primary role of an operating system (OS)?
OS is a program interface between applications and hardware, controls application program execution.
What are the three main objectives of an operating system?
Convenience, efficiency, ability to evolve.
List some functions of an operating system related to program development and execution.
Program development, program execution, access IO devices.
What is the role of an operating system in managing resources in a computer system?
The OS is responsible for managing the resources for the movement, storage, and processing of data.
What is a function in terms of computer software?
A program or suite of programs executed by the processor that frequently relinquishes control and depends on the processor to allow it to regain control.
What are some reasons for the evolution of operating systems over time?
Hardware upgrades, new types of hardware, new services, and fixes are some reasons for the evolution of operating systems.
What are the stages in the evolution of operating systems?
The stages include serial processing, simple batch systems, multiprogrammed batch systems, and time-sharing systems.
Describe the characteristics of serial processing in the context of operating systems.
In serial processing, computers ran without an operating system, programmers interacted directly with the hardware, and users accessed the computer in series.
What were the problems associated with serial processing in early computers?
Problems included scheduling difficulties, where time allocations could run short or long resulting in wasted computer time, and setup time spent on setting up programs to run.
What were the characteristics of simple batch systems in the evolution of operating systems?
In simple batch systems, computers were expensive, users no longer had direct access to the processor, and jobs were submitted to a computer operator who batched them together.
What was the role of the monitor in a simple batch system?
The monitor in a simple batch system maximized processor utilization by queuing jobs and routing them to the processor when available.
What is the purpose of setting up Simple Batch Systems?
To maximize processor utilization and save costs on early expensive computers.
In Simple Batch Systems, who monitors user activities?
The computer operator, as users no longer have direct access to the processor.
What happens to a job after it is submitted in a Simple Batch System?
The job is batched together with other jobs by the computer operator and placed on an input device.
What occurs when a program finishes execution in a Simple Batch System?
The program branches back to the monitor for further monitoring and control.
What is a Resident Monitor responsible for?
Controlling the sequence of events and always staying in memory
What does the Monitor do after reading in a job?
It gives control to the job
What happens after a job returns control to the Monitor?
The processor executes instructions from the memory containing the monitor
What happens when the processor encounters an ending or error condition in a user program?
Control is passed back to the job
When control is returned to the monitor, what is the processor doing?
Fetching and executing instructions from the monitor program
What is JCL (Job Control Language)?
A special type of programming language used to provide instructions to the monitor
What is the purpose of Memory Protection for the monitor?
To prevent a job from monopolizing the system and ensure user program execution does not alter the monitor's memory area
What can only be executed by the monitor?
Timer
What do Privileged instructions allow the OS to do?
Have more flexibility in controlling user programs
What are the two Modes of Operation?
User Mode and Kernel Mode
In which mode does a user program execute?
User Mode
What restrictions are there in User Mode?
Certain areas of memory are protected from user access and certain instructions may not be executed
In which mode does the monitor execute?
Kernel Mode
What is allowed in Kernel Mode?
Execution of privileged instructions and accessing protected areas of memory
What is User Mode in operating systems?
User program executes in user mode, certain areas of memory are protected from user access, and certain instructions may not be executed.
What is Kernel Mode in operating systems?
Monitor executes in kernel mode, privileged instructions may be executed, and protected areas of memory may be accessed.
What is a Uniprogrammed Batch System?
A system where the processor is often idle even with automatic job sequencing and IO devices are slow compared to the processor.
What does the processor do in a Uniprogrammed Batch System when it reaches an IO instruction?
It must wait until that IO instruction concludes before proceeding.
What is Multiprogramming also known as?
Multitasking.
How many programs can be held in memory in the Multiprogramming scenario described?
Three, four, or more programs.
In a Simple Batch System, what alternates the processor time?
Between the execution of user programs and execution of the monitor.
What is given over to the monitor in a Simple Batch System?
Some main memory and some processor time.
What does the Simple Batch System sacrifice in order to improve utilization of the computer?
Some main memory and some processor time.
What is a computer?
A computer is an electronic device that can store, process, and retrieve data.
What are the main components of a computer?
The main components of a computer are the central processing unit (CPU), memory, storage devices, input devices, and output devices.
What is the function of the central processing unit (CPU) in a computer?
The CPU is the brain of the computer responsible for executing instructions, performing calculations, and managing data flow.
What is RAM in a computer?
RAM (Random Access Memory) is a type of computer memory that is used to temporarily store data and program instructions that the CPU needs to access quickly.
What is the difference between RAM and storage devices like hard drives?
RAM is volatile memory that loses its data when the computer is powered off, while storage devices like hard drives are non-volatile and retain data even when the power is off.
What are input devices in a computer?
Input devices are hardware components that allow users to interact with a computer by providing data and commands, such as keyboards, mice, and scanners.
What are output devices in a computer?
Output devices are hardware components that display or present data that has been processed or retrieved by the computer, such as monitors, printers, and speakers.
What is Uniprogramming?
A system where only one program is executed at a time on the CPU.
What is Multiprogramming?
A system where multiple programs are loaded into the memory and executed concurrently.
What is CPU 7016 in the context provided?
It refers to a specific type or model of CPU.
What is Response Time in the context provided?
The time taken for a system to respond to a given input or request.
What is the response time for JOB 1?
5 minutes.
What is the response time for JOB 2?
20 minutes.
What is the response time for JOB 3?
30 minutes.
What is the average response time for the jobs given?
18 minutes.
What does Throughput refer to in this context?
The number of jobs processed within a specific time frame.
How many jobs are completed in 30 minutes according to the throughput data?
3 jobs.
How many jobs are completed in 1 hour according to the throughput data?
6 jobs.
What is the available memory size mentioned in the example?
250 Mb.
How is the Processor time utilized in Multiprogramming systems?
Shared among multiple users and programs.
What is the effect of Multiprogramming on Resource Utilization according to Table 22?
It can handle multiple interactive jobs efficiently.
How do multiple users access a system in Multiprogramming with Time Sharing?
Simultaneously through terminals with the OS interleaving the execution of each user program.
What is Batch Multiprogramming versus Time Sharing compared in Table 23?
Different approaches to managing multiple programs on a system.
What was CTSS?
Compatible Time Sharing System, one of the first time sharing operating systems developed at MIT by Project MAC.
How much memory did the computer running CTSS have?
32000 36-bit words of main memory.
How much memory did the resident monitor of CTSS consume?
5000 36-bit words of main memory.
How often did the time slicing system clock generate interrupts in CTSS?
Approximately one every 0.2 seconds.
What were the stages in the evolution of operating systems mentioned in the text?
Serial Processing, Simple Batch Systems, Multiprogrammed Batch Systems, Time Sharing Systems.
What are some major advances in development in operating systems?
Processes, Memory management, Information protection and security, Scheduling and resource management
What is a process in the context of operating systems?
A process can be defined as a program in execution, an instance of a running program, the entity that can be assigned to and executed on a processor, a unit of activity characterized by a single sequential thread of execution, a current state, and an associated set of system resources
Causes of Errors: Nondeterminate program operation
Program execution is interleaved by the processor when memory is shared, the order in which programs are scheduled may affect their outcome
Causes of Errors: Deadlocks
It is possible for two or more programs to be hung up waiting for each other, may depend on the chance timing of resource allocation and release
Causes of Errors: Improper synchronization
A program must wait until the data are available in a buffer, improper design of the signaling mechanism can result in loss or duplication
Causes of Errors: Failed mutual exclusion
More than one user or program attempts to make use of a shared resource at the same time, only one routine at a time is allowed to perform an update against the file
Execution Context Importance
It is the internal data by which the OS is able to supervise and control the process. It includes the contents of the various process registers, information such as the priority of the process, and whether the process is waiting for the completion of a particular IO event
Components of a Process
An executable program, the associated data needed by the program (variables, work space, buffers, etc.), and the execution context or process state of the program
Process Management
The entire state of the process at any instant is contained in its context. New features can be designed and incorporated into the OS by expanding the context to include any new information needed to support the feature
What components does a process contain?
An executable program, the associated data needed by the program (variables, work space, buffers, etc.), and the execution context or process state of the program.
What is the role of Process Management in an operating system?
Process Management involves managing the entire state of a process at any instant, including its context, to support features and allocate resources effectively.
What are the five principal storage management responsibilities of the operating system?
Process isolation, automatic allocation and management, support of modular programming, protection and access control, and long-term storage management.
What is the purpose of process isolation in storage management?
Process isolation ensures that each process operates independently and does not interfere with other processes, providing a secure and reliable environment.
How does the operating system support modular programming in storage management?
The OS allows for modular programming by managing and allocating resources efficiently, enabling the integration of new features and enhancements.
What is the significance of protection and access control in storage management?
Protection and access control mechanisms ensure that processes have the necessary permissions to access resources, safeguarding data integrity and preventing unauthorized access.
What role does scheduling play in process management?
Scheduling involves assigning resources and managing the execution order of processes to optimize performance, improve efficiency, and meet system requirements.
What is the purpose of resource management in process management?
Resource management involves allocating and monitoring system resources such as memory, CPU time, and I/O devices to ensure optimal utilization and prevent resource contention.
How does a process access memory in a logical point of view in memory management?
Processes can address memory logically without considering the physical memory constraints, allowing multiple jobs to reside in main memory concurrently for efficient execution.
What is the scenario described when there is a total of 10M free memory but cannot fit a 10M program (5M + 5M)?
The scenario describes a memory allocation issue where the free memory is fragmented into two separate blocks of 5M each, making it impossible to allocate a contiguous block of 10M for the program.
What is a facility that allows programs to address memory from a logical point of view without regard to the amount of main memory physically available?
Virtual Memory
What was virtual memory conceived to meet the requirement of?
Having multiple user jobs reside in main memory concurrently
What is the problem when there is a total of 10M free memory but a 10M program cannot fit (5M + 5M)?
Fragmentation
What are pages in a process termed as?
Fixed size blocks
How is a word referenced in a program through virtual addressing?
Via a virtual address consisting of a page number and an offset within the page
What provides for a dynamic mapping between virtual and physical addresses in main memory?
Virtual memory
What does the nature of the threat concerning an organization depend on?
Circumstances
What is the main issue in controlling access to computer systems and stored information?
Security
What are the key responsibilities of an operating system in managing resources?
Processes, Memory Management, Information Protection, Security, Scheduling, Resource Management
What must resource allocation policies consider in managing resources?
Fairness, differential responsiveness, and efficiency
What is monolithic architecture in an operating system?
OS is a single process that uses a single binary file, manages everything (memory, devices, scheduling, networking, etc.), and manages via system calls. It may be modular (e.g. device drivers added as modules). Examples include Unix, Linux, Windows.
What is microkernel architecture in an operating system?
Assigns only a few essential functions to the kernel. This approach includes address spaces, interprocess communication (IPC), basic scheduling, simplifies implementation, provides flexibility, and is well-suited to a distributed environment.
What is multithreading in operating systems?
A technique in which a process executing an application is divided into threads that can run concurrently. A thread is a dispatchable unit of work that includes a processor context and its own data area to enable subroutine branching. Threads execute sequentially and are interruptible.
What is symmetric multiprocessing in operating systems?
Symmetric multiprocessing is a system in which two or more identical processors are connected to a single shared main memory and execute simultaneously. It offers improved performance through parallel processing.
What are distributed operating systems?
Distributed operating systems manage a group of independent computers and make them appear to be a single computer system. They involve multiple machines working together to achieve a common goal, often with shared resources and communication channels.
What is object-oriented design in operating systems?
Object-oriented design involves organizing software components as objects that interact with each other to accomplish tasks. It focuses on modularity, encapsulation, and reusability of code, facilitating easier maintenance and scalability of the system.
What is the timing of application related events?
The timing of application related events refers to the specific timing or scheduling of events related to the application process.
What does SMP stand for?
Symmetric Multiprocessing
What is SMP in the context of computer hardware architecture?
It refers to a hardware architecture where multiple processors can run processes in parallel, and the OS manages scheduling and synchronization among processors.
What are the advantages of SMP?
1. Performance: Multiple processes can run simultaneously on different processors. 2. Availability: Failure of a single process does not halt the system. 3. Incremental Growth: Performance can be enhanced by adding additional processors. 4. Scaling: Vendors can offer a range of products based on the number of processors configured.
What does SMP provide in terms of operating systems?
SMP provides the illusion of a single main memory space, single secondary memory space, and unified access facilities. It is the state of the art for distributed operating systems.
How is Object-Oriented Design utilized in SMP systems?
Object-Oriented Design is used for adding modular extensions to a small kernel, enabling customization of an operating system without disrupting system integrity. It eases the development of distributed tools and full-blown distributed operating systems.
What does Fault Tolerance refer to?
Fault Tolerance refers to the ability of a system or component to continue normal operation despite hardware or software faults. It typically involves redundancy to increase system reliability, albeit at a cost in financial terms or performance.
What are the fundamental concepts related to SMP?
The basic measures related to Symmetric Multiprocessing systems.
What is the purpose of adding modular extensions to a small kernel?
Enables programmers to customize an operating system without disrupting system integrity
How does fault tolerance contribute to a system's operation?
Refers to the ability of a system or component to continue normal operation despite the presence of hardware or software faults
What are some fundamental concepts related to fault tolerance?
Reliability, Mean Time to Failure (MTTF), Mean Time to Repair (MTTR), and Availability
Define Reliability (Rt) in the context of fault tolerance.
Reliability is defined as the probability of correct operation up to time t given that the system was operating correctly at time t o
What is the Mean Time to Failure (MTTF) in fault tolerance?
Mean Time to Failure (MTTF) is the average time until a system fails
Explain the concept of Mean Time to Repair (MTTR) in fault tolerance.
Mean Time to Repair (MTTR) is the average time it takes to repair or replace a faulty element
Define Availability in the context of fault tolerance.
Availability is the fraction of time the system is available to service users' requests
What does fault tolerance typically involve in terms of system redundancy?
Fault tolerance typically involves some degree of redundancy to increase system reliability
What is the fraction of time the system is available to service users requests?
Availability ratio
What is a Permanent fault?
a fault that after it occurs is always present, and persists until the faulty component is replaced or repaired
What is a Temporary fault?
a fault that is not present all the time for all operating conditions
What is a Transient fault?
a fault that occurs only once
What is an Intermittent fault?
a fault that occurs at multiple unpredictable times
What is Spatial physical redundancy?
involves the use of multiple components that either perform the same function simultaneously or are configured as backups
What is Temporal redundancy used for?
involves repeating a function or operation when an error is detected; effective with temporary faults but not useful for permanent faults
What does Information redundancy provide?
fault tolerance by replicating or coding data so that bit errors can be detected and corrected
What are some Operating System Mechanisms for fault tolerance?
process isolation, concurrency control, virtual machines, checkpoints, and rollbacks
Who wrote the initial version of Linux?
Linus Torvalds, a Finnish student of computer science
When was Linux first posted on the Internet?
in 1991
What is the key to the success of Linux?
availability of free software packages, high modularity, and easy configuration
What is a characteristic of Linux's source code availability?
It is free and open source, allowing users to access and modify the code
What platforms can Linux run on?
several platforms
How is Linux described in terms of functionality?
a full-featured UNIX system that includes virtually all of the OS functionality in one large block of code
What type of system was Linux initially based on?
a UNIX variant for the IBM PC
What is Linux?
An OS software that supports fault tolerance, process isolation, concurrency control, virtual machines, checkpoints, and rollbacks.
Who created the initial version of Linux?
Linus Torvalds, a Finnish student of computer science.
When was Linux first posted on the Internet?
1991.
What is key to the success of Linux?
The availability of free software packages.
How is Linux structured in terms of modules?
As a collection of loadable modules, relatively independent blocks that can be linked and unlinked from the kernel at runtime.
What happens to a module at runtime when it is unlinked from the kernel?
A module is executed in kernel mode on behalf of the current process.
What components make up the Linux Kernel?
Kernel Components
What is the purpose of an operating system interface?
To provide a user-friendly way to interact with the computer system.
What happens when you run a program on an operating system?
The program is loaded into memory and executed by the CPU.
What is the role of a resource manager in an operating system?
To allocate and manage resources such as CPU time, memory, and devices efficiently.
How has the evolution of operating systems progressed over time?
From simple serial processing to batch processing, multiprogramming, time-sharing, and beyond.
What are some major achievements in the development of operating systems?
Improvements in process management, memory management, information protection, security, and scheduling algorithms.
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Chapter 2 flashcards: Understanding the role and functions of an operating system in a computer system.
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