Operating Systems
Who’s in charge here?
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What is an Operating System
 Basically
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 ROM
 The 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 graphics
 Multitasking – Allow multiple programs
to run at the same time
 Multiprocessing – Allow different parts
of the same program to run at once

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What does that look like?
10
Preventing Chaos
 The
OS is responsible for preventing
application conflicts and potential
deadlocks
WHAT???
11
Scenario
 Dylan
(the user) is running several
different applications (multitasking)
MSN Messenger
Microsoft Word
iTunes – Music Player
Firefox - Web browser
12
But the processor can only do
one thing at a time…
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Chaos Solution
3
2
1
4
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Chaos solution
 The
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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Summary
 The
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/fall2
002/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/Lect
11h6.pdf
 http://www.it.iitb.ac.in/~sudhir/mypapers/OOOS.ppt
 http://www.linux.org
 http://www.sauder.ubc.ca/bcom/course_resou
rces/comm4382/docs/OSTrends.ppt
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