The Operating System - Managing Resources Flashcards

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1
Q

What is an an operating system?

A

=> The name given to the collection of systems software responsible for managing a computer.
=> Manages the computer’s resources including peripherals, processes, memory protection and backing store.
=> Hides the functioning of the computer from the users and their programs.

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2
Q

What is a ‘kernal’?

A

The core of an OS and what the operating system is based upon.

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3
Q

What are ‘resources’?

A

Any physical or virtual component in a computer system that is of limited availability.

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4
Q

What are peripherals?

A

=> External hardware components that can be connected to a computer.

=> Each peripheral has its own machine code, as well as its own rules for how it transmits/receives data from the computer. These rules create a protocol for the OS to control the device.

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5
Q

What is a driver?

A

A piece of software that is required by the operating system to control a peripheral device.

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6
Q

How does an operating system manage memory?

A

=> Data is loaded in RAM when it is needed and unloaded when it is not needed.

=> Memory can be partitioned so that portions of memory are allocated for particular tasks. It can also use memory as a buffer when transferring data between the computer and a slower device e.g. webcam.

=> Memory protection is used to control memory access rights on a computer; its main purpose is to prevent a process from accessing memory that has not been allocated.

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7
Q

What is memory addressing?

A

=> Refers to the exact position in RAM that a byte of data occupies.

=> The memory manager has the job of allocating where in RAM data gets put. We don’t have direct access to this on modern data computers.

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8
Q

What is memory paging?

A

=> A memory management scheme by which the computer stores and retrieves data from secondary storage for use in main memory; the operating system retrieves data from secondary storage in same-size blocks called pages.

=> An important part of virtual memory implementations in modern operating systems, where we use secondary storage to let programs exceed the size of available physical memory.

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9
Q

What is memory segmentation?

A

=> An operating system memory management technique where a computer’s primary memory is divided into segments or sections.

=> A reference to a memory location includes a value that identifies a segment and an offset (memory location) within that segment.

=> Segments or sections are also used in object files of compiled programs when they are linked together into a program image and when the image is loaded into memory.

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10
Q

What is a backing store?

A

=> (Typically) a part of the hard disk that is used as a paging system to store data that is not currently in the main memory.

=> OS creates a hierarchical directory structure for storing data and presents it to the user.

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11
Q

What are the similarities and differences between the use of backing stores in Windows machines and MAC machines?

A

=> Similar:
Both use Journaling (a way of ensuring that crashes during mid-write/delete etc on a sector of data don’t cause exceptions in the state of the disk) for fault tolerance.

=> Different:
In modern-day operating systems, Windows uses NTFS and Macs use HFS Plus.

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12
Q

What are meta-journaling and block journaling?

A

=> Meta-journaling:
The action is stored in a log before it is carried out.

=> Block journaling:
Stores the data change first, before committing to disk.

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13
Q

How does the operating system control processes?

A

=> Via signals that are sent to and from the CPU to control what is happening, and the order in that processes occur.
=> By using CPU scheduling to ensure that the CPU is being used to its full extent.

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14
Q

What is CPU scheduling?

A

=> Allows one process to be carried out while another is on hold (waiting), for actions such as the input of data.

=> Operating system must select a queued process whenever the CPU is idle.

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15
Q

What are the three states of processing?

A

=> Ready - in main memory, awaiting execution.
=> Running - currently being executed.
=> Blocked - awaiting access to a resource that is currently unavailable e.g., database, file, etc.

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16
Q

What is polling?

A

Sending a signal to a device, such as a printer, to check if it is ready. A device normally has to respond to polling several times to demonstrate it is ready.

17
Q

What is threading?

A

=> A thread is a sequence of instructions that make up part of a process.
=> Two threads that belong to the same process can share resources (such as a network connection).
=> Two processes don’t usually share resources.

18
Q

What is an interrupt?

A

Halting the normal fetch-execute cycle and diverting focus to the event that has triggered the interrupt e.g. mouse click, new hardware, software fault.

19
Q

What utility software is built into operating systems?

A

=> Anti-virus - notify the user of anything suspicious and give options for removal/quarantine of the software (when UTD).

=> Compression - Reduces file storage requirements of a file/s.

=> Debuggers - Identify and resolve problems with software.

=> Screensavers - Start automatically to prevent screen burn, and to save power.

=> System Monitors/Task Managers - Track memory, processor usage, network traffic, and other metrics.

=> File Managers - Move, copy, delete, and rename files.

20
Q

What is the purpose of the user interface?

A

=> Allows a user to enter and receive information.

=> A text-based user interface (command-line interface, CLI) requires the user to type commands into the screen at a prompt.

=> A graphical user interface (GUI) the functions are carried out by clicking buttons, icons and menus using a pointing device, such as a mouse.

21
Q

What utility software is built into an OS to perform UI tasks?

A

=> Command Line Interface (CLI):
+ Minimal hardware requirements.
+ Commands give experienced users more specific control.
- Less experienced users will encounter a steep learning curve.

=> Graphical User Interface (GUI):
+ Intuitive.
+ No need to memorize commands.
+ Help facilities tend to be on offer.
+ Promotes multitasking as many windows can be open at once.
- High requirements for hardware,
- Experienced users can be slowed down by an excessively helpful interface.

22
Q

What is ‘batch processing’?

A

=> Occurs when the operating system collects together programs and data that are then processed in a batch.
=> Often happens over an extending time frame e.g. fortnightly.
=> E.g. calculating and printing pay slips.

23
Q

What is ‘real time transaction’?

A

=> Real time processing systems process data as it is received rather than gathering it in batches.
=> E.g. selling arena tickets (data needs updating immediately to avoid the same seat being sold twice).

24
Q

What is ‘real time control’?

A

RTC processing is time critical and used in time limited situations, e.g. air traffic control.

25
Q

What are the different types of OS?

A

Single User:
=> Found on personal computers.
=> Only one user can be logged on at a time, although, they can perform multiple tasks at the same time.

Multi-user:
=> Allows multiple users to be logged onto the system at the same time, and time-sharing of resources is enabled.
=> E.g., network admin systems for managing user accounts.

Multi-tasking and multi-programming:
=> Allows for multiple apps to be run simultaneously.
=> Multi-tasking allows for applications to be swapped in and out of the CPU.
=> Multi-programming stores more than one program in memory and optimizes the use of the CPU preventing it from being idle.
=> Apps are given time slices to use the CPU.
=> A single-user and multi-user can use multi-tasking and multi-programming.