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Operating Systems

Who’s in charge here?

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What is an Operating SystemBasically the boss of the computer

Facilitate communication Maximize throughput Minimize processing time Optimize computer resources Organize files Provide security Monitor system/alert user

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Operating System (OS)Allows the user (you) to interact with:

Applications (word, email, Internet) File management (open, save, delete) Networking (connects to the Internet) Hardware (CD drives, printers, scanners) Memory (loading, sharing, saving) Security (permissions, passwords)

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Where does the OS Live?Some computers store their operating

system in ROM (such as cell phones and MP3 players)

Others include only part of it in ROMThe remainder of the operating system

is loaded into memory (RAM) in a process called booting, which occurs when you turn on the computer

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What does the OS Look Like?The end user has a pleasant Graphical

User Interface (GUI) which represents the OS

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Who are the players? Microsoft Windows (90% of market share)

DOS/Windows 3.1 Windows NT/95/98/ME/2000/XP/Vista

Apple – Mac OS X Unix and variants

BSD, Sun Solaris, Unisys Linux (FREE)

Palm OS / iPhone OS

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Microsoft Windows Originally, Microsoft Windows was a type of

program, known as a shell, which put a graphical face on MS-DOS

With the introduction of Windows 95 in 1995, Microsoft began transitioning Windows from an operating system shell into a full operating system that seldom showed its MS-DOS roots

The latest Windows versions have no ties at all to the DOS past

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UNIX and Linux Multiple User Operating Systems UNIX was developed at Bell Labs before

personal computers were available Linux was created by Linus Torvalds and

continues to be a work-in-progress Allow a timesharing computer to communicate

with several other computers or terminals at once Linux is free for anyone to use or improve UNIX remains the dominant operating system for

Internet servers

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Common Features of an OS Graphical User Interface (GUI) - Using

mouse and graphicsMultitasking – Allow multiple programs

to run at the same timeMultiprocessing – Allow different parts

of the same program to run at once

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What does that look like?

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Preventing ChaosThe OS is responsible for preventing

application conflicts and potential deadlocks

WHAT???

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ScenarioDylan (the user) is running several

different applications (multitasking)

Microsoft Word iTunes – Music Player

Firefox - Web browser

MSN Messenger

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But the processor can only do one thing at a time…

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Chaos Solution

1 2

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Chaos solutionThe processor does a bit of work for

MS Word (1), then a little bit of iTunes (2), a little bit of MSN (3), and a bit of Firefox (4) and goes back to the start.

The processor moves so fast that it looks like its running all 4 programs at once.

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SummaryThe Operating System is the BOSS

Applications (word, email, Internet) File management (open, save, delete) Networking (connects to the Internet) Hardware (CD drives, printers, scanners) Security (permissions, passwords)

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Sources http://www.cse.buffalo.edu/~bina/cse421/

fall2002/sept3.ppt http://www.cse.nd.edu/courses/cse341/

www/notes/Chapter-01.ppt http://www.essdack.org/tips/page3.htm http://www.int.gu.edu.au/courses/2010int/

Lect11h6.pdf http://www.it.iitb.ac.in/~sudhir/mypapers/OO-

OS.ppt http://www.linux.org http://www.sauder.ubc.ca/bcom/

course_resources/comm4382/docs/OSTrends.ppt