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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