Lecture 6 Operating System CSCS100 - Spring 2008 – Forman Christian College Asher Imtiaz Wajeeha Akram *Several of these slides have been adapted and modified from LUMS CS101 course (Dr Umar Saif and Sohaib Khan), VU CS101 slides (Dr. Altaf A. Khan) and Peter Norton’s supplementary material.
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Lecture 6 Operating System CSCS100 - Spring 2008 – Forman Christian College Asher Imtiaz Wajeeha Akram *Several of these slides have been adapted and modified.
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Lecture 6Operating SystemCSCS100 - Spring 2008 – Forman Christian CollegeAsher ImtiazWajeeha Akram
*Several of these slides have been adapted and modified from LUMS CS101 course (Dr Umar Saif and Sohaib Khan), VU CS101 slides (Dr. Altaf A. Khan) and Peter Norton’s supplementary material.
Goals• What is Operating System?• Understand the role of Operating System
Operating Systems• You have already had ample experience with at
least one of them• IBM PCs commonly come with Windows XP
Operating System… Some may have Windows 2000 on them
• Macs have MAC OS operating system• Sun machines use UNIX or LINUX operating
systems• Palm PDAs come with PalmOS
• Operating systems is how Bill Gates got so rich!
What is an Operating System?• An operating system is a ‘program’, a piece of
software, rather than hardware• It is the first program to be loaded in memory,
after POST is completed• It is a rather special program – it manages the
computer and everything that runs on it• Amongst other things, the operating system
provides you with a User-Interface, so you can actually use the computer
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Functions of Operating Systems• Provide a user interface• Run programs• Manage hardware devices• Organized file storage
What does an Operating System do?
Applicationse.g.
MS Word, Calculator
Useri.e.YOU
Operating Systeme.g.
Windows 2000
HardwareCPU, Monitor, Keyboard
You can think of the operating system as a factory manager, who manages resources, inventory, workers and jobs
What does an Operating System do?
• The operating system manages a lot of things
• Including• Memory• Processor• Other hardware• Applications• File System
computer in it which manages the keypad, the display, as well as does computations about cooking
• Microwave ovens do not need an operating system, because they do the same simple task over and over again
• An oven runs a single program all the time
• All desktop computers have an operating system
• The operating system creates the ability to:• Serve a variety of purposes• Interact with the user in
more complicated ways• At a simple level, OS
does two things• Manages hardware and
software resources• Provides a way for the user
to deal with hardware, without knowing all its details
Multi-tasking
Providing a User Interface• User Interface (UI)
• How a user interacts with a computer• Require different skill sets
• Graphical User Interface (GUI)• Most common interface
• Windows, OS X, Gnome, KDE
• Uses a mouse to control objects• Uses a desktop metaphor• Shortcuts open programs or documents• Open documents have additional objects• Task switching• Dialog boxes allow directed input
Graphical User Interface
Providing a User Interface• Command line interfaces
• Older interface• DOS, Linux, UNIX
• User types commands at a prompt• User must remember all commands• Included in all GUIs
Running Programs• Many different applications supported• System call
• Provides consistent access to OS features
• Share information between programs• Copy and paste• Object Linking and Embedding
Managing Hardware• Programs need to access hardware• Interrupts
• CPU is stopped• Hardware device is accessed
• Device drivers control the hardware
Organizing Files and Folders• Organized storage• Long file names• Folders can be created and nested• All storage devices work consistently
Enhancing an OS• Utilities
• Provide services not included with OS• Goes beyond the four functions• Firewall, anti-virus and compression• Prices vary
Useful link to understand more about operating systems…