Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

McGraw-Hill Technology EducationMcGraw-Hill Technology Education Copyright © 2006 by The McGraw-Hill Companies, Inc. All

rights reserved.

Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

McGraw-Hill Technology Education

Peter Norton

Operating System Basics

Operating System Basics

4 Basic Functions of OS

• Displays the on-screen elements with which you interact—the user interface.

• Loads programs (such as word processing and spreadsheet pro-grams) into the computer's memory so that you can use them.

• Coordinates how programs work with the computer's hardware and other software.

• Manages the way information is stored on, and retrieved from disks.

Types of Operating Systems

• Real Time OS• Single User Single Tasking OS• Single User—Multi Tasking OS• Multi User—Multi Tasking OS

Types of OS (RTOS)

• A real-time operating system (RTOS) is an operating system (OS) intended to serve real-time application requests.

• It must be able to process data as it comes in, typically without buffering delays.

• A common example of an RTOS is an HDTV receiver and display. It needs to read a digital signal, decode it and display it as the data comes in.

Types of OS (RTOS)

• Real-time operating system– Very fast small OS– Built into a device– Respond quickly to user input– MP3 players, Medical devices, HDTV

receiver

Types of OS (RTOS)

Some of the best known, most widely deployed, real-time operating systems are:

• LynxOS• OSE• QNX• RTLinux• VxWorks• Windows CE

RTOS full forms

• UNICS - UNiplexed Information Computing System

• UNICS became Unix• OSE = Operating System Embedded• QNX = QNX is Not Unix• Linux = Linus Torvalds and Unix

Single user/Single tasking OS

– One user works on the system

– Performs one task at a time

– MS-DOS and Palm OS

– Take up little space on disk

– Run on inexpensive computers

Single user/Single tasking OS

Single user/Multitasking OS

– User performs many tasks at once

– Most common form of OS

– Windows XP, 7, 8 and OS X (MAC OSX)

– Require expensive computers

– Tend to be complex compared to SUST

Single user/Multitasking OS

Multi user/Multitasking OS

– Many users connect to one computer

– Each user has a unique session

– UNIX, Linux, and VMS*

– Maintenance can be easy

– Requires a powerful computer*Virtual Memory System

Multi user/Multi tasking OS

7A-15

4 Functions of Operating Systems

1. Provide a user interface

2. Run programs

3. Manage hardware devices and software

4. Organized file storage

1) Providing a User Interface

• User interface– How a user interacts with a computer

– Require different skill sets of understanding:• Tabs• Mouse• Cursors• Dialogue Boxes • Pop-up menus etc.

Providing a User Interface

• A) Graphical user interface (GUI)

• B) Command Line User Interface

Providing a User Interface

• A) Graphical user interface (GUI)– Most common interface

• Windows, OS X, Gnome, KDE (Cross)

– Uses a mouse to control objects– Uses a desktop metaphor– Shortcuts opening programs or documents– Open documents have additional objects– Task switching– Dialog boxes allow directed input

Graphical User Interface (Win 7)

Graphical User Interface (Win 8)

Graphical User Interface (Osx)

Graphical User Interface (GNOME 3.12)

Graphical User Interface (GNOME 3.12)GNOME is developed by The GNOME Project

Composed of both volunteers and paid contributors

The largest corporate contributor being Red Hat

Open Source and Multi-platform based

Graphical User Interface (KDE)

Providing a User Interface

• B) Command line interfaces– Older interface

• DOS, Linux, UNIX

– User types commands at a prompt– User must remember all commands– Included in all GUIs

Command Line Interface

2) Running Programs

OS supports many different application

• OS provides for System call– In computing, a system call is how a program

requests a service from an operating system's kernel that it does not normally have permission to run.

2) Running Programs

System call (Continued)

– This may include hardware related services (e.g. accessing the hard disk) and creating and executing new processes.

– System calls provide an essential interface between a process and the operating system.

Running Programs

Other services:

• Saving the contents of files to a disk.

• Reading the contents of a file from disk into memory.

• Sending a document to the printer and activating the printer.

Running Programs

Other services (Continued):

• Providing resources that let you copy or move data from one document to another, or from one program to another.

• Allocating RAM among the running programs.

• Recognizing keystrokes or mouse clicks and displaying characters or graphics on the screen.

Running Programs

• Share information between programs– Copy and paste– Object Linking and Embedding

Example:

From “Paint” to “Word”

Running Programs

3) Managing Hardware

• Programs need to access hardware…

• Hardware accessing procedure:– Interrupt request sent to CPU– CPU is stopped– Hardware device is accessed– CPU retrieves the information– CPU show it @ monitor

• Device drivers control the hardware

Managing Hardware

4) Organizing Files and Folders

• Organized storage

• Long file names

• Folders can be created and nested

• All storage devices work consistently

Organizing Files and Folders

Enhancing an OS

• Utilities– Provide services not included with OS– Goes beyond the four functions– May be Free or Paid or part of the OS

Category:– Backing up and compression– Firewall– Anti-virus / Internet Security– Screen-savers

Enhancing an OS

• Backup software– Archives files @ removable media

– Ensures data integrity

– Most OS include a backup package

– Many third party packages exist– Nova, Easeus, Paragon, Shadow, Acronics

Backup Software

Enhancing an OS

• Anti-virus software– Crucial utility– Finds, blocks and removes viruses– Must be updated regularly– McAfee, Norton Anti-Virus, E-set, Panda,

Avira

Enhancing an OS

• Anti-virus Vs Internet Security

– 1.Antivirus is a class of software that detects and cleans out virus infected files while Internet Security is a suite of applications that aims to protect users against threats from the internet

– 2.Internet Security suites usually include an antivirus application among other programs

Enhancing an OS

• Anti-virus Vs Internet Security– 3.Internet security suites commonly includes a

firewall, anti malware, anti spyware, and email protection.

– 4.Internet Security suites often cost more than stand-alone antivirus applications

– 5. Internet Security requires more resources to run and slows down old computers

Enhancing an OS

• Firewall– It looks at the Internet traffic going in and

out of your machine.

– You can instruct them to block certain traffic or allow other kinds.

– Sometimes you can choose to do this automatically without the firewall asking, and sometimes you can choose to have the firewall ask you first before blocking.

Enhancing an OS

• Firewall (Hard Vs Soft)– Hard– Built in a device (router)– Soft– Programmed in a system (Utility)

Enhancing an OS

• Intrusion detection– Often part of a firewall package– Announces attempts to breach security– Creates Logs

Enhancing an OS

• Antivirus Vs Firewall:

• Firewalls are used to limit incoming transmissions to those that are least likely to contain bad data,

• while antivirus programs actually look at the effect that the incoming data has on the system.

• Firewalls cannot be used to remove threats if they happen to get past the firewall. Antivirus can be used to do the same.

Enhancing an OS

• Screen savers– Crucial utility for command line systems

• Prevents burn-in of image (ghost image) in the monitor

– Merely fun for GUI systems– Screen saver decorates idle screens

Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

McGraw-Hill Technology Education

Peter Norton

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