2.1 Systems Software (OCR A Level Computer Science) Flashcards
Exam code: H446
1/72
0Still learning
Know0
- FrontOperating Systems
Define operating system.
Was this flashcard deck helpful?
Cards in this collection (72)
Define operating system.
An operating system is system software that manages hardware and software resources and provides an interface between the user and the hardware.
What are the main functions of an operating system?
The main functions of an operating system are resource management, file management, interrupt handling, security, providing a platform for software to run, providing a user interface, and providing utilities.
Operating systems provide an interface between the user and the , allowing the user to interact with the system and run .
Operating systems provide an interface between the user and the hardware, allowing the user to interact with the system and run applications.
How does an operating system manage resources when multiple applications are open?
The operating system allocates memory and CPU time to each application, and manages the input and output processes so all running applications can function efficiently.
Define interrupt handling.
Interrupt handling is the process by which the operating system responds quickly to events that need immediate attention, such as user input or hardware signals, to maintain system efficiency.
True or False?
Operating systems can restrict user accounts from installing unapproved software.
True.
Operating systems often allow system accounts to be restricted from certain actions, such as installing unapproved software or changing other users’ settings, to improve security.
Utility programs such as and help maintain and secure the computer system.
Utility programs such as file encryption and disk cleanup help maintain and secure the computer system.
What is the difference between a GUI and a CLI provided by an operating system?
A GUI (Graphical User Interface) allows users to interact with the system visually, while a CLI (Command-Line Interface) allows users to interact using text commands.
Define memory management.
Memory management is a fundamental role of the operating system, dealing with the allocation and deallocation of primary memory.
Which three main techniques are used to make memory management more efficient?
The three main techniques are paging, segmentation and virtual memory.
What is paging?
Paging is a method of dividing primary memory into equal-sized blocks called pages.
True or False?
Paging can lead to internal fragmentation.
True.
Paging can cause internal fragmentation when pages are not filled completely, leaving wasted space.
If a 200KB file is divided into four 64KB Pages, the last Page would have of unused space.
If a 200KB file is divided into four 64KB Pages, the last Page would have 56KB of unused space.
Define virtual memory.
Virtual memory is when the computer uses secondary storage as an extension of main memory, allowing more applications to run when RAM is full.
What is a major drawback of over-relying on virtual memory?
Over-reliance on virtual memory can lead to performance issues, as accessing data in virtual memory is much slower than accessing RAM.
Virtual memory creates an illusion of a memory and enables applications to continue to multitask.
Virtual memory creates an illusion of a larger memory and enables applications to continue to multitask.
What is segmentation?
Segmentation is a method of dividing memory into variable-sized blocks corresponding to types of data needed by an application.
True or False?
Segmentation can lead to external fragmentation.
True.
Segmentation can cause external fragmentation because memory gaps between segments may prevent new segments from being allocated efficiently.
Segmentation is space-efficient because it only allocates space depending on an application needs.
Segmentation is space-efficient because it only allocates space depending on the amount an application needs.
Name one benefit and one drawback of each memory management technique: paging, segmentation, and virtual memory.
Paging: Efficient allocation but can cause internal fragmentation. Segmentation: Space-efficient but can cause external fragmentation. Virtual memory: Allows multitasking but is slower than RAM.
Define interrupt.
An interrupt is a signal to the processor that causes it to suspend its current task and temporarily execute a different task.
What is the purpose of interrupts in computer systems?
The purpose of interrupts is to allow real-time event handling, device communication, and multitasking by letting the processor temporarily stop its current task to handle urgent events.
When an interrupt occurs, the processor the current program execution and transfers control to an .
When an interrupt occurs, the processor suspends the current program execution and transfers control to an Interrupt Service Routine (ISR).
Define Interrupt Service Routine (ISR).
An Interrupt Service Routine (ISR) is a special function designed to handle a specific interrupt type quickly and efficiently.
What is the difference between hardware interrupt and software interrupt?
A hardware interrupt is generated by external devices (e.g. keyboard input), while a software interrupt is triggered by software or the operating system (e.g. application errors).
The interrupt process includes saving the contents of the in memory before handling the interrupt, and restoring them after the completes.
The interrupt process includes saving the contents of the processor registers in memory before handling the interrupt, and restoring them after the ISR completes.
True or False?
The processor can handle a new interrupt even while it is already executing an ISR, if the new interrupt has higher priority.
True.
This is known as interrupt nesting, where higher-priority interrupts can interrupt lower-priority ISRs.
Define interrupt priority.
Interrupt priority is the mechanism that allows the processor to determine which interrupt to handle first, especially when multiple interrupts occur simultaneously.
Define scheduling.
Scheduling is the process of deciding which tasks to process, for how long, and in what order, using scheduling algorithms.
What are the two main categories of CPU scheduling algorithms?
The two main categories of CPU scheduling algorithms are pre-emptive and non-pre-emptive.
Pre-emptive scheduling allocates the CPU for a specific to a process and allows .
Pre-emptive scheduling allocates the CPU for a specific time quantum to a process and allows interruption of processes.
Define Round Robin scheduling.
Round Robin scheduling is a pre-emptive algorithm that gives each process a fixed time quantum and cycles through all processes in a queue.
What is the main drawback of First Come First Served (FCFS) scheduling?
The main drawback of FCFS scheduling is that long processes can block shorter or higher-priority tasks, leading to poor performance or delays.
In scheduling, once the CPU is allocated to a process, it holds the CPU until or switches to a waiting state.
In non-pre-emptive scheduling, once the CPU is allocated to a process, it holds the CPU until completion or switches to a waiting state.
Define Multi-Level Feedback Queue (MLFQ) scheduling.
Multi-Level Feedback Queue scheduling is a pre-emptive priority algorithm where processes are organised into multiple queues, with shorter and more critical tasks processed first.
What is the difference between Shortest Job First (SJF) and Shortest Remaining Time First (SRTF) scheduling?
SJF is non-pre-emptive and schedules jobs based on the shortest total burst time, while SRTF is pre-emptive and always runs the process with the shortest remaining time to completion.
The algorithm ensures all processes get a fair share of CPU time, but choosing the right can be difficult.
The Round Robin algorithm ensures all processes get a fair share of CPU time, but choosing the right time quantum can be difficult.
Which scheduling algorithm is most likely to cause starvation of long processes?
The Shortest Job First (SJF) algorithm can cause long processes to starve if short jobs keep arriving.
Define burst time.
Burst time is the total time required by a process on the CPU without interruption.
True or False?
Multi-Level Feedback Queue algorithms are non-pre-emptive.
False.
Multi-Level Feedback Queue algorithms are pre-emptive and allow interruption and reordering of processes.
Define operating system (OS).
An operating system (OS) is fundamental software that manages computer hardware, provides services for programs, and acts as an interface between users and the machine.
What is the main purpose of an operating system?
The main purpose of an operating system is to manage computer hardware and software resources, and to provide services for computer programs.
A system is designed to process tasks in specific timeframes, which is critical for systems like self-driving cars.
A real-time operating system is designed to process tasks in specific timeframes, which is critical for systems like self-driving cars.
True or False?
Multi-user operating systems allow only one user to access computer resources at a time.
False.
Multi-user operating systems support multiple users accessing resources concurrently.
Define embedded operating system.
An embedded operating system is designed to run specific tasks inside devices that are not primarily computers, such as microwaves or IoT devices.
A distributed operating system runs on multiple that appear as a single unit, allowing efficient task .
A distributed operating system runs on multiple machines that appear as a single unit, allowing efficient task distribution.
Give one example of a multi-tasking operating system.
Windows, MacOS, or Linux are examples of multi-tasking operating systems.
An embedded operating system usually performs a set of features very .
An embedded operating system usually performs a simple set of features very efficiently.
Define BIOS.
The BIOS is the Basic Input/Output System of a computer, a piece of firmware stored on the motherboard that initializes hardware and starts the operating system.
Where is the BIOS stored in a computer system?
The BIOS is stored on a small memory chip on the computer's motherboard.
On system start, the BIOS is the software to run.
On system start, the BIOS is the first software to run.
What is the purpose of the POST (Power-On Self-Test) performed by the BIOS?
The POST (Power-On Self-Test) is a diagnostic test performed by the BIOS to ensure all hardware components are working properly before the operating system loads.
True or False?
If the BIOS detects an error during POST, the boot process continues as normal.
False.
If the BIOS finds an error during POST, it will halt the boot process or show an error message.
If POST is successful, the BIOS runs the loading sequence to start the operating system.
If POST is successful, the BIOS runs the bootstrap loading sequence to start the operating system.
What happens if a computer's BIOS is destroyed or overwritten?
If the BIOS is destroyed or overwritten, the computer cannot initialise its hardware or load the operating system, making it unable to start.
The BIOS performs a POST, which stands for .
The BIOS performs a POST, which stands for Power-On Self-Test.
Define device driver.
A device driver is a piece of software that enables communication between an operating system and a specific hardware device.
What is the purpose of a device driver?
The purpose of a device driver is to allow the operating system to interact with and control a hardware device.
True or False?
A device driver enables the operating system to communicate with hardware devices such as printers and graphics cards.
True.
A device driver allows the operating system to communicate with specific hardware devices like printers and graphics cards.
Why might a single computer have several printer drivers installed?
A single computer may have several printer drivers installed because each printer model requires its own driver software.
A device driver the gap between the operating system and the hardware device.
A device driver bridges the gap between the operating system and the hardware device.
Give an example of how a device driver allows an operating system to interact with hardware.
For example, a printer driver enables the operating system to send print commands and manage print jobs on a printer.
Most hardware manufacturers write their own software for their devices.
Most hardware manufacturers write their own device driver software for their devices.
What role does a device driver play when adding new hardware, such as a DVD drive, to a computer?
A device driver must be installed so the operating system can communicate with and control the new hardware, such as a DVD drive.
Define virtual machine.
A virtual machine is a software-driven computer that runs within a physical machine, mimicking a full computer system with its own operating system and applications.
What is the primary purpose of a hypervisor in virtual machine technology?
A hypervisor is software that allows multiple virtual machines to run on a single physical machine by managing and allocating hardware resources to each VM.
True or False?
A virtual machine can run its own operating system and applications independent of the host system.
True.
Each virtual machine acts as a separate computer, running its own operating system and applications independently from the host OS.
Some programming languages, such as Java, compile to , which can be executed by a .
Some programming languages, such as Java, compile to intermediate code, which can be executed by a virtual machine.
What is cross-platform compatibility and how do virtual machines enable it?
Cross-platform compatibility means software can run on different operating systems. Virtual machines enable this by mimicking different OS environments, allowing users to run applications not natively supported by their main OS.
Running software in a allows developers to test their programs in a safe and environment that does not affect the host operating system.
Running software in a virtual machine allows developers to test their programs in a safe and isolated environment that does not affect the host operating system.
State one benefit and one drawback of using virtual machines.
A benefit is the ability to run software on different operating systems. A drawback is slower performance compared to running directly on physical hardware.
Why might a developer use a virtual machine to run a previous version of an operating system?
A developer might use a virtual machine to run a previous OS version to support legacy applications that are incompatible with the latest release.
Sign up to unlock flashcards
or