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Operating Systems > Fundamentals Of Operating System > Flashcards

Fundamentals Of Operating System Flashcards

1
Q

What is an operating system?

A

An operating system is a set of programs that control how a computer system works, especially how memory is used and how different programs work together.

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2
Q

What are some common examples of operating systems?

A

Common examples of operating systems include Windows, Linux, and macOS.

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3
Q

How does Cambridge University Press (2013) define an operating system?

A

Cambridge University Press (2013) defines an operating system as “a set of programs that control the way a computer system works, especially how its memory is used and how different programs work together.”

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4
Q

What is the Cambridge University Press (2009) definition of an operating system?

A

Cambridge University Press (2009) defines an operating system as “the set of programs that a computer uses to operate, store files, and communicate with devices and other computers.”

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5
Q

What is the Cambridge University Press (2011) definition of an operating system?

A

Cambridge University Press (2011) defines an operating system as “a program that controls the way a computer works, and that allows applications (programs for particular purposes) to work on it.”

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6
Q

How does the International Organization for Standardization (2015) describe an operating system?

A

The International Organization for Standardization (2015) describes an operating system as “software that controls the execution of programs and that may provide services such as resource allocation, scheduling, input-output control, and data management.”

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7
Q

What is the Merriam-Webster definition of an operating system?

A

Merriam-Webster defines an operating system as “software that controls the operation of a computer and directs the processing of programs (as by assigning storage space in memory and controlling input and output functions).”

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8
Q

What keywords can be used to categorize the tasks of an operating system?

A

Keywords include supporting computer operating nodes, organizing program management, providing a user interface, managing resources, monitoring the system, and ensuring system security.

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9
Q

What source does the course on operating systems follow for its structure?

A

The course follows the standards outlined in Modern Operating Systems by Andrew S. Tanenbaum (2015).

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10
Q

According to Tanenbaum (2015), what are the central tasks of an operating system?

A

The central tasks of an operating system, according to Tanenbaum (2015), are “to provide user programs with a better, simpler, cleaner model of the computer and to handle managing hardware resources.”

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11
Q

What role does hardware abstraction play in the function of an operating system?

A

Hardware abstraction allows the operating system to provide a simplified model of the computer, making it easier for user programs to interact with the hardware without managing its complexity directly.

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12
Q

What is the core building block of any computer system?

A

The core building block of any computer system is the processor or central processing unit (CPU).

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13
Q

What is the von Neumann cycle?

A

The von Neumann cycle is the continuous process by which the CPU fetches, decodes, and executes instructions until the computer is shut down.

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14
Q

Who developed the concepts behind the von Neumann architecture?

A

The von Neumann architecture was developed by Hungarian-American scientist John von Neumann in 1945.

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15
Q

What are the key elements of the von Neumann architecture?

A

The key elements are the central processing unit (CPU), main memory, input/output components, and the communication system.

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16
Q

What are the two main units of the CPU in the von Neumann architecture?

A

The CPU consists of the control unit and the arithmetic logic unit (ALU).

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17
Q

What is the role of the control unit in the CPU?

A

The control unit is responsible for executing the program, fetching instructions from memory, decoding them, and coordinating their execution.

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18
Q

What does the arithmetic logic unit (ALU) do?

A

The ALU performs arithmetic and logical calculations within the CPU.

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19
Q

What is the function of registers within the CPU?

A

Registers are fast buffers within the CPU that store the results of calculations temporarily for quick access.

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20
Q

What is the defining feature of the main memory in the von Neumann architecture?

A

The main memory features random access memory (RAM), allowing the CPU to read and write data and instructions in any order.

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21
Q

What role do input/output components play in the von Neumann architecture?

A

Input/output components handle communication between the system and the environment, such as with users or storage devices.

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22
Q

How does the communication system in the von Neumann architecture work?

A

The communication system uses bus systems (e.g., address bus, data bus) to facilitate communication between the CPU, main memory, and other components.

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23
Q

What are the five steps of the von Neumann cycle?

A

The five steps are: Fetch instruction, Decode instruction, Fetch operand, Execute instruction, and Store result.

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24
Q

What happens during the fetch instruction step in the von Neumann cycle?

A

The CPU loads a program instruction from the main memory for processing.

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25
Q

What is machine language, and why is it important in the decode instruction step?

A

Machine language is the numerical format in which instructions are stored in memory, and it is specific to each processor family.

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26
Q

What happens during the execute instruction step of the von Neumann cycle?

A

The arithmetic logic unit (ALU) performs the actual calculation, such as adding two numbers or jumping to another address.

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27
Q

What is instruction pipelining, and how does it improve CPU performance?

A

Instruction pipelining allows the CPU to process multiple instructions in overlapping stages, completing one instruction per clock cycle.

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28
Q

What is vector processing in modern CPUs?

A

Vector processing allows modern CPUs to perform calculations across a set of operands simultaneously, commonly used in applications like computer games and scientific simulations.

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29
Q

What are caches, and why are they important in modern CPUs?

A

Caches are layers of fast memory between the CPU and slower main memory, allowing the CPU to process data more quickly without being slowed down by memory access times.

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30
Q

What is a multicore system, and how does it differ from earlier CPU designs?

A

A multicore system consists of multiple logical CPUs (cores) on a single processor chip, allowing for parallel processing within a single physical processor.

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31
Q

What role does the operating system play in the von Neumann architecture?

A

The operating system manages and controls the execution of applications and facilitates the interaction between software and hardware in a von Neumann architecture.

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32
Q

What is the core of an operating system called, and in what mode is it executed?

A

The core of an operating system is called the kernel, and it is executed in a privileged mode (kernel mode).

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33
Q

What happens if an application tries to call privileged machine instructions directly?

A

An error occurs, which is handled by the operating system.

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34
Q

What is the distinction between user mode and kernel mode?

A

User mode restricts applications from directly accessing hardware, while kernel mode allows the operating system to execute privileged instructions to manage hardware safely.

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35
Q

How do applications interact with hardware if direct access is prohibited?

A

Applications interact with hardware through the operating system, using system calls encapsulated in system libraries.

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36
Q

What happens during an interrupt or exception in a CPU?

A

The program counter is loaded with a new address (usually in the kernel), and the CPU switches to kernel mode to handle the interrupt or exception.

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37
Q

What is the role of the interrupt controller in the CPU?

A

The interrupt controller manages and processes exceptions or interruptions by switching to the appropriate address in the kernel and saving the old execution thread.

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38
Q

How does the operating system support different operating modes?

A

The operating system supports modes like real-time operation, multi-user operation, batch processing, and virtualization to meet various computing needs.

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39
Q

What is the role of the operating system in managing program execution?

A

The operating system ensures that when one program finishes, another is executed, managing multiple programs and ensuring smooth transitions between them.

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40
Q

What kind of user interfaces do modern operating systems typically provide?

A

Modern operating systems provide graphical user interfaces (GUIs) for user interaction and command-line interfaces (CLIs) for administrators.

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41
Q

What is a device driver, and why must it be executed in kernel mode?

A

A device driver is a set of program code that controls communication between the computer and attached hardware. It must be executed in kernel mode to access the hardware directly.

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42
Q

What are the responsibilities of an operating system in user, device, and resource management?

A

The operating system manages user accounts, device access through drivers, and core resources like the CPU and memory, ensuring secure and efficient operation.

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43
Q

How does the operating system ensure system security?

A

The operating system protects against unauthorized access, prevents system crashes from program errors, and manages resources efficiently in multi-user environments.

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44
Q

What role does system monitoring play in an operating system?

A

System monitoring allows the operating system to detect and handle critical issues, ensuring system stability and logging data for administrative troubleshooting.

45
Q

What are system calls, and what role do they play in hardware abstraction?

A

System calls are special function calls provided by the operating system that allow applications to interact with hardware through standardized interfaces without accessing hardware directly.

46
Q

What is the difference between a program and a process in the context of an operating system?

A

A program is a sequence of machine instructions, while a process is a program in execution.

47
Q

What role does the process control block (PCB) play in managing processes?

A

The PCB stores the status of each process, including the program counter and other execution-related information, enabling the operating system to manage multiple processes.

48
Q

How does an operating system manage multiple processes when there are more processes than CPU cores?

A

The operating system switches between processes based on their needs, updating the program counter and selecting the next process for execution.

49
Q

What are the three main process states?

A

The three main process states are: Active, Ready, and Blocked.

50
Q

What happens when a process is blocked?

A

The process is paused and taken off the CPU while waiting for input/output operations to complete. Once the needed data or resources are available, it transitions from ‘blocked’ to ‘ready.’

51
Q

What is cooperative multitasking?

A

Cooperative multitasking relies on processes to make system calls to allow other processes to use the CPU, but non-cooperative processes can monopolize the CPU if they don’t make system calls.

52
Q

What is preemptive multitasking, and how does it work?

A

Preemptive multitasking uses hardware interrupts (like a time slice or ‘hardware alarm clock’) to allow the operating system to regain control of the CPU, preventing processes from monopolizing it.

53
Q

What is a time slice in preemptive multitasking?

A

A time slice is the maximum amount of time a process can use the CPU before an interrupt occurs, allowing the operating system to perform a process switch.

54
Q

What happens if a time slice expires without a system call?

A

The operating system preempts the process, saves its state, and can switch to another process or continue with the current process, depending on the queue and priorities.

55
Q

How can a program utilize multiple CPUs or cores simultaneously?

A

A program can be designed to use multiple CPUs or cores through threading, where different threads of execution within the same process can run on different processors.

56
Q

What are threads, and how do they relate to processes?

A

Threads are smaller units of execution within a process, allowing tasks to be run concurrently. Multiple threads share the same process address space.

57
Q

What is the difference between user-level and kernel-level threads?

A

User-level threads are managed at the application level, without the operating system’s knowledge. Kernel-level threads are managed by the operating system, allowing them to be executed on different CPUs simultaneously.

58
Q

What is simultaneous multithreading (Hyper-Threading), and how does it differ from software threads?

A

Simultaneous multithreading is a hardware feature that allows a single CPU to present itself as multiple logical processors, enabling better hardware resource utilization. Unlike software threads, it is managed at the hardware level.

59
Q

Why is process switching between threads less resource-intensive when managed by the same CPU?

A

When threads are managed by the same CPU, they share the same address space, which avoids the overhead of switching between different processes, making execution faster.

60
Q

What is the central resource in a computing system alongside the CPU?

A

The main memory is the central resource alongside the CPU in a computing system.

61
Q

How is the main memory managed in modern operating systems?

A

The operating system abstracts and manages the main memory, often using techniques like virtual memory management.

62
Q

What problem arises from frequent memory allocation and release?

A

Memory fragmentation, where small free memory chunks are scattered, preventing allocation of large memory blocks.

63
Q

What is the ‘First Fit’ memory allocation strategy?

A

The ‘First Fit’ strategy searches for the first free memory block large enough for the allocation request and uses it.

64
Q

How does the ‘Best Fit’ strategy allocate memory?

A

The ‘Best Fit’ strategy searches for the free block with the smallest remainder after allocation to minimize wasted space.

65
Q

What is the ‘Worst Fit’ strategy in memory allocation?

A

The ‘Worst Fit’ strategy searches for the free block with the largest remainder, aiming to leave bigger usable fragments.

66
Q

Why is memory protection essential in multitasking systems?

A

Memory protection ensures that processes can only access their own memory, preventing them from affecting other processes or accessing sensitive data.

67
Q

What hardware feature supports memory protection in a CPU?

A

The CPU uses boundary registers to check the validity of addresses and trigger exceptions for memory access violations.

68
Q

What is the purpose of logical addresses in memory management?

A

Logical addresses allow processes to operate as if they have exclusive access to memory, which is then mapped to physical addresses by the MMU.

69
Q

How does the Memory Management Unit (MMU) convert logical addresses to physical addresses?

A

The MMU uses the base and limit registers to convert logical addresses to physical addresses by adding the base value to the logical address.

70
Q

What problem is solved by using virtual memory and paging?

A

Paging solves the problem of needing contiguous physical memory for processes, allowing memory blocks (pages) to be allocated in non-contiguous frames.

71
Q

What are the physical memory blocks called in paging?

A

Physical memory blocks in paging are called page frames.

72
Q

How is the virtual address space organized in a 32-bit processor using paging?

A

In a 32-bit processor, the virtual address space is divided into pages, with each page mapped to a physical memory frame.

73
Q

What is the purpose of the Translation Lookaside Buffer (TLB)?

A

The TLB is a cache that stores recently used page table entries, allowing faster address translation without frequent memory lookups.

74
Q

How does the TLB improve memory access speed in paging systems?

A

The TLB speeds up memory access by caching recent translations of virtual addresses to physical addresses, avoiding repeated searches in the page tables.

75
Q

What is demand paging?

A

Demand paging is a system where pages are loaded into memory only when accessed.

76
Q

What is demand paging?

A

Demand paging is a system where pages are loaded into memory only when accessed, allowing more efficient use of physical memory.

77
Q

What happens when there are no free page frames in memory during demand paging?

A

The operating system will swap out rarely used pages to the hard disk to free up memory for new page allocations.

78
Q

What is the FIFO page replacement strategy?

A

FIFO (First In, First Out) replaces the page that has been in memory the longest.

79
Q

How does the Least Recently Used (LRU) strategy select a page for replacement?

A

LRU selects the page that has not been accessed for the longest time for replacement.

80
Q

What is the Not Recently Used (NRU) replacement strategy?

A

NRU uses flags (ACCESSED and DIRTY) set by the MMU to select pages that have not been recently accessed and have not been modified for replacement.

81
Q

What happens if no pages meet the NRU criteria of being both not accessed and unchanged?

A

The system selects a page that has been accessed but not modified (ACCESSED=1, DIRTY=0), or if necessary, a modified page.

82
Q

How is the main memory of a computer addressed by the CPU?

A

The main memory is addressed with byte granularity by the CPU.

83
Q

How does the hard disk differ in terms of access granularity compared to main memory?

A

Hard disks are accessed in larger blocks, typically a few kilobytes, instead of individual bytes.

84
Q

Why do hard disks work in a block- or sector-oriented manner?

A

This is due to the design of hard disks, where the read/write heads need to be positioned on the correct track, and data is read when the sector passes under the head.

85
Q

What does LBA stand for, and how is it used in file systems?

A

LBA stands for Logical Block Addressing, and it refers to a linear address space used by the operating system to organize data on hard disks in blocks.

86
Q

What is a file system, and how does it abstract hard disk access for users?

A

A file system groups data under a file name, making it manageable as one logical unit. It abstracts the block-based structure of the hard disk into files and directories.

87
Q

What attributes do files usually have in modern file systems?

A

Files have attributes such as length, size, ownership, access permissions, and timestamps.

88
Q

What method is commonly used in modern file systems to manage files?

A

Hierarchical file management through folders and directories.

89
Q

What is formatting in the context of file systems?

A

Formatting is the process of setting up a disk to use a particular file system.

90
Q

What are the two meanings of the term ‘file system’?

A

It can refer to the algorithm used for file management in the operating system or the data format written to the disk.

91
Q

What is an inode in inode-based file systems?

A

An inode is a data structure that contains meta-information about a file, such as its size and access permissions, but not the actual file content.

92
Q

Where are inodes stored, and why must they persist across reboots?

A

Inodes are stored on the hard disk to ensure that file information is retained when the computer is switched off.

93
Q

How does an inode link to the actual contents of a file?

A

Inodes contain references (logical block addresses) to the data blocks where the actual contents of the file are stored.

94
Q

What happens if the references in an inode are insufficient for a larger file?

A

Indirect references are used, which point to blocks containing additional references, allowing for larger files to be managed.

95
Q

What are double and triple indirect references in inode-based systems?

A

Double and triple indirect references are pointers that lead to blocks containing more references, enabling the management of very large files.

96
Q

How are directories implemented in inode-based file systems?

A

A directory is essentially a file containing a table that maps file names to inode addresses, enabling the organization of files within directories.

97
Q

How does backward navigation work in a directory tree?

A

There is usually an entry named ‘..’ that refers to the inode of the parent directory.

98
Q

Why does the root directory not have a name?

A

The root directory is referred to by a placeholder (usually ‘/’) because file names are not stored in inodes.

99
Q

What is the significance of inode #1 in the root directory?

A

Inode #1 refers to the data block that contains the directory entries for the root directory.

100
Q

What is the basic concept that practically all modern computers follow?

A

The von Neumann architecture.

101
Q

What are the primary components of the von Neumann architecture?

A

A central processing unit (CPU), main memory, and the communication infrastructure between them.

102
Q

Why is system software needed in computers?

A

To encapsulate repetitive hardware-related tasks and abstract the hardware with protection mechanisms.

103
Q

What core tasks are performed by the operating system in a von Neumann-based computer?

A

The operating system manages abstraction concepts, such as process management and memory protection.

104
Q

How does the operating system enable the CPU to be used efficiently by several programs?

A

By dividing CPU time into time slices for multiple application programs.

105
Q

What role does memory protection play in a computer system?

A

It ensures that different programs do not interfere with each other unintentionally.

106
Q

How does virtual memory abstract the main memory for processes?

A

Virtual memory allows each process to see the address space as an exclusive resource.

107
Q

What is demand paging, and how is it related to virtual memory?

A

Demand paging is a technique used to load pages of memory only when they are needed, further abstracting main memory.

108
Q

How are hard disk space and file systems integrated into the abstraction concepts provided by the operating system?

A

Hard disk space and file systems are smartly integrated, providing storage and management for files within the abstraction of the system.

Operating Systems (4 decks)

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