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Introduction to Basic OS Concepts
Submitted to
Mr. Manu
Prepared By
Mayank Joshi
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Topics Covered
What is an Operating System?
Mainframe Systems
Desktop Systems Multiprocessor Systems
Distributed Systems
Clustered System Real -Time Systems
Handheld Systems
Computing Environments
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What is an Operating System?
A program that acts as an intermediarybetween a user of a computer and the
computer hardware. Operating system goals:
Execute user programs and make solving user
problems easier. Make the computer system convenient to use.
Use the computer hardware in an efficientmanner.
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A little insight
Computer systems typically contain:-
Hardware and Software componentsHardware electronic/electric, mechanicalcomponentsSoftware programs and subprograms
Without support softwares, the computer isof very little use
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What is an OS?
An interface between Hardware and UserPrograms
An abstraction of the hardware for all the(user) processes
i.e. hides the complexity of the underlyinghardware and give the user a better view of
the computer
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Computer System Components
1. Hardware provides basic computing resources (CPU,memory, I/O devices).
2. Operating system controls and coordinates the use of thehardware among the various application programs for thevarious users.
3. Applications programs define the ways in which the systemresources are used to solve the computing problems of theusers (compilers, media players,database systems, videogames, business programs).
4. Users (people, machines, other computers).
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Abstract View of SystemComponents
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How the OS interacts??
. . .CPU
memory
device device device
Operating system
utilitiesapplications
software
systemssoftware
hardwarecomponents
. . .CPU
memory
device device device
Operating system
utilitiesapplications
software
systemssoftware
hardwarecomponents
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Operating System Components
Resource allocator manages andallocates resources.
Control program controls theexecution of user programs andoperations of I/O devices .
Kernel the one program runningat all times (all else beingapplication programs).
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The Goals of an OS
Let users run programs:
Correctness
Memory boundaries, priorities, steady state
Convenience
User should not handle the tiny details
(encapsulation/abstraction), providesynchronization primitives, system calls, filesystem, tools
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The Goals of an OS
OS lets the users run programs whilefocusing on :
Maximizing Efficiency
Resource Utilization, resource Sharing,Multitasking
Fairness (in resource allocation) Among: users, tasks, resources
The tradeoff between efficiency and fairness
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An OS is a Resource Allocator
Its good to share!
Multiple users get all computing resourcessimultaneously: CPU time
Memory (ram, swap, working set, virtual etc)
File system (storage space, primary and secondarystorage devices)
I/O devices (display, printers, mouse,keyboard) Clock
The OS should give every user the illusion thathe/she is getting all resources exclusively (not
sharing!)
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What an OS does for a living??
loop forever {
run the process for a while.stop the process and save its state.
load state of another process.
}
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Virtual Continuity
A process can get switched in or switched
out.
OS should give the illusion for the process asif it exists in the CPU continuously
=> Context Switching
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There are OSs where a process is forced to give upthe CPU (e.g. when stayed for too long).
Such systems implement a preemptive schedulingpolicy.
Examples includeWindows (NT,XP & 7) , Unix etc
Preemptive Scheduling
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Most OSs provide the priority mechanism
Priorities are associated with processes
Priorities are used to help the OS reach fairness
Using Priorities
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Process
A processis a program in execution.
The components of a process are:
the program to be executed,
the data on which the program will execute,
the resources required by the programsuch as
memory, file(s)and the status of the execution (wait, ready, running).
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OS Features Needed for
Multiprogramming I/O routine supplied by the system.
Memory management the systemmust allocate the memory toseveral jobs.
CPU scheduling the system must
choose among several jobs readyto run.
Allocation of devices.
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Time-Sharing SystemsInteractive
Computing The CPU is multiplexed among several jobs that are
kept in memory and on disk (the CPU is allocated to
a job only if the job is in memory). A job may be swapped into and out of memory
On-line communication between the user and thesystem is provided; when the operating system
finishes the execution of one command, it seeks thenext control statement from the users keyboard.
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Desktop Systems
Personal computers computer system dedicatedto a single user.
I/O devices keyboards, mice, display screens,small printers.
User convenience and responsiveness.
Can adopt technology developed for larger
operating system often individuals have sole useof computer and do not need advanced CPUutilization of protection features.
May run several different types of operatings stems Windows Mac OS UNIX Linux
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Distributed Systems
Distribute the computation among several physicalprocessors.
Loosely coupled system each processor has its own localmemory; processors communicate with one another throughvarious communications lines, such as high-speed buses ortelephone lines.
Advantages of distributed systems. Resources Sharing
Computation speed up load sharing
Reliability
Communications
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Distributed Systems (cont)
Requires networking infrastructure.
Local area networks (LAN) or Widearea networks (WAN)
May be either client-server or peer-
to-peer systems.
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Major Computer OSs
Windows by Microsoft Corp.
Unix
Linux(freeware with openSUSE,redhat andUbuntu distributions)
MacOS by Apple Inc.
Solaris by Sun Microsystems
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Leading Mobile OSs
Windows Mango,Windows mobile for PDAs
iOS for iPhones
Android by Google for touch screen devices
(tablets and smartphones)
Symbian OS (s30,s40,s60, anna and belle) byNokia
PalmOS Meego
BADA by Samsung
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Sources
www.wikipedia.com
www.google.co.in
www.microsoft.com www.linuxdeveloperforum.com
www.apple.inc
http://www.google.co.in/http://www.microsoft.com/http://www.linuxdeveloperforum.com/http://www.apple.inc/http://www.apple.inc/http://www.linuxdeveloperforum.com/http://www.microsoft.com/http://www.google.co.in/8/2/2019 mjos
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THANK YOU
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