Operating Systems Flashcards
What is a operating system?
1) A set of software that controls the computer’s hardware and resources and provides services for computer programs.
2) It has control over processes, files, memory, and devices.
The OS manages and schedules processes, controls file systems, allocates memory and interacts with hardware devices. It ensures that each program and user gets the necessary resources without interference. It also provides essential services like input/output management, security, and multitasking.
2 types of operating systems - GUI based (windows/apple) and CLI based (some versions of Linux)
Functions of operating system (5)
1) Provides a user interface
2) Does memory management
3) Does peripheral management
4) Allows multi-tasking (resource allocation)
5) Provides security
User Interface
OS has to provide a link between the user and the
computer hardware.
Types of user interface (4)
1) Graphical User Interfaces (GUIs) that have menus and icons,
2) Command Line Interfaces (CLIs) (Linux) where the user types in codes,
3) Natural Language Interface (siri) (NLIs) where the user speaks to the interface
4) Menu Based Interface (MBIs) which gives the user a selection of
options.
Memory Management
1) Memory management is done by keeping track of storage devices (like HDD).
2) Controlling which application has access to which area of memory (RAM), allocate memory (RAM) to programs.
3) Modify memory locations - Reorganizing data in the RAM.
4) Each location in memory can be read, modified, and written to by the OS. When the memory location is full the OS sends a confirmation message.
File management (2)
1) Similarly, the OS provides file management services by sorting out where data is stored on the disk drives and memory.
2) The OS allows users to organize files in folders as well as to copy and delete fi les.
Peripheral management
1) The process of handling the interaction between a computer system and its peripheral devices. For example printers, scanners, keyboards, mice, monitors, external storage devices, and other input/output devices.
2) Coordinate with BIOS (basic input/ output system)
3) Use device drivers to interface with peripherals
Device drives translate peripheral signal. A device driver is a software program which allows hardware devices to be used by the OS. They act as translators between the devices and the computer
system, enabling the system to read from and write to disks.
What is a peripheral
A peripheral is an external device that connects to a computer and provides input, output, or additional functionality
Multi- tasking
1) Multi Tasking is an operating system which allows user to perform more than one computer task (program, process, thread) at a time.
2) Another technique to distribute the CPU’s time is time slicing, which involves dividing the CPU’s time into equal intervals called the time quantum.
3) Each task in the ready queue is given an equal share of the CPU’s time, regardless of the time required to execute.
4) When a task’s allocated time slice expires, it is paused, and the next task in the queue gets the CPU. This process continues in a cyclic manner, ensuring fairness and responsiveness in multitasking systems.
5) Time slicing is commonly used in Round Robin scheduling, where no task can monopolize the CPU, promoting balanced execution across all tasks.
What is CPU Scheduling
CPU scheduling is a method used by the operating system to allocate the CPU’s time among tasks.
There are two main types of CPU scheduling: Preemptive and Non-Preemptive.
1) In Non-Preemptive scheduling, once a task is allocated the CPU, it runs to completion or until it voluntarily moves to a waiting state, with no interruptions allowed.
- Tasks are executed in a queue-based manner, where the next task gets the CPU only after the current task is fully completed, regardless of its priority or execution time.
2) On the other hand, Preemptive scheduling allows the CPU to interrupt the current task if a higher-priority task enters the ready queue or if the current task’s time slice expires. This ensures that critical or time-sensitive tasks are handled promptly, though it introduces more overhead due to frequent context switching.
Security
1) OS prevents unauthorised access.
2) It ensures security of the system through
usernames and passwords.
3) The OS protects files from other users reading or
writing files.
What are the different application softwares? (7)
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Students Do Everything With Graphic Display Calculators
1) Word processing: A program for storing, manipulating, and formatting text entered from a keyboard and providing a printout.
e.g. MS Word, Google Docs.
2) Spreadsheets: A program in which data is arranged in the rows and columns of
a grid and can be manipulated and used in calculations.
e.g. MS Excel, Open Office Calc.
3) Database Management System (DBMS): A database management system (DBMS) is system software for
creating and managing databases. The DBMS provides users and programmers with a systematic way to create, retrieve, update and manage data.
e.g. MS Access.
4) Web browsers: A software application for retrieving, presenting, and traversing
information resources on the World Wide Web
e.g. Chrome, IE, MF. Access, retrieve, present content on WWW.
.
5) Email: Exchange of digital
messages to email server, recipient receives message when they connect to server
e.g. Gmail (web-based) or MS Outlook (software-based).
6) Computer Aided Design (CAD): Programs that use computer systems to assist in the creation,
modification, analysis, or optimization of a design
e.g. Autodesk AutoCAD, Google Sketchup, and Dassault Systemes Solid Works.
7) Graphic processing: Graphics software or image editing software is a program or collection of programs that enable a person to manipulate visual images on a computer.
e.g Adobe Photoshop, Adobe Illustrator, GIMP.
OS vs Application features
1) Certain parts of the interface are provided by libraries in the OS and certain parts are specific to each application
For example: the menu bar and buttons are standard, but the specifics/pictures are up to the individual application
What are the common features of most programmes (4)
1)Toolbars
2) Menus
3) Dialogue Boxes
4) GUI components
System Software vs Application Software
1) System Software: Software that manages and controls computer hardware, such as an OS (1 mark). Example: Windows, Linux (1 mark).
2) Application Software: Software designed for end-users to perform specific tasks (1 mark). Example: Microsoft Word, Google Chrome (1 mark).
WYSIWYG (What you see is what you get)
Software that accurately reflects the appearance of the finished product.
What is WIMP
Windows, Icons, Menus, and Pointers
WIMP is a model used in graphical user interfaces (GUIs). It allows users to interact with the computer system through visual elements (like windows and icons) rather than text-based commands.
