Transcript Types of Operating Systems

Operating System
Topics to include
Operating System
Layers of OS
Functions of OS
Types of OS
Operating System
• A program that controls the execution of
application programs
• An interface between applications and
hardware
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Operating System Objectives
• Convenience
– Makes the computer more convenient to use
• Efficiency
– Allows computer system resources to be used in an
efficient manner
• Ability to evolve
– Permit effective development, testing, and
introduction of new system functions without
interfering with service
Layers of Computer System
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Functions of Operating Systems
• Provide a user interface
• Run programs
• Manage hardware devices
• Organized file storage
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Providing a User Interface
• User interface
– How a user interacts with a computer
– Require different skill sets
Providing a User Interface
• Graphical user interface (GUI)
– Most common interface
• Windows, OS X, Gnome, KDE
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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
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
Managing Hardware
• Programs need to access hardware
• Interrupts
– CPU is stopped
– Hardware device is accessed
• Device drivers control the hardware
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Types of Operating Systems
• Real-time operating system
– Very fast small OS
– Built into a device
– Respond quickly to user input
– MP3 players, Medical devices
• 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 Tasking
• Operating System cannot be able to take control back
from the running process/task/application
• In case if a process call an I/O Instruction then
Processor must wait for I/O instruction to complete
before preceding
Multitasking
• Operating System can take control back from the
running process and can give it to other.
• When one job needs to wait for I/O, the processor can
switch to the other job
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