Overview of Computer ScienceOverview of Computer ScienceOverview of Computer ScienceOverview of Computer Science

Copyright © 2007 Brian A. Kell

CSC 101 — Fall 2007CSC 101 — Fall 2007

Lecture 32 — November 12, 2007Lecture 32 — November 12, 2007

Operating Systems, Operating Systems, Open Source Systems, Open Source Systems, Intellectual PropertyIntellectual Property

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AnnouncementsAnnouncements

• Lab #10 tomorrow

• Quiz #5 coming up on Friday

• Research paper is due next Monday (11/19)– Monday of Thanksgiving Week– If you can’t turn it in on Monday, turn it in earlier– Submit it in two ways:

• Printed paper copy• Submit file on Blackboard• Both versions are required by the due date

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ObjectivesObjectives

• Operating Systems/Linux

• Open source software

• “Web 2.0”

• Intellectual property– Trademarks– Patents– Trade secrets– Copyrights

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Anatomy of an Operating SystemAnatomy of an Operating System

• Functional components of a basic OS:1.Supervisor2.Input/Output control drivers3.Memory Manager4.File Manager5.User Interface

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1. Supervisor1. Supervisor

• Oversees and controls execution of all processes• Loads and executes applications• Manages requests (also called system calls or interrupts)

initiated by users and applications for things such as:– Printing

– File I/O

– Networking

– Keyboard input

– Display output

– Etc.

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2. I/O Control Drivers2. I/O Control Drivers

• I/O control drivers provide the communication between running applications and input/output devices– Printers – Mouse and keyboard– Disks – Screen – Etc.

• Drivers hide details of I/O devices from users and processes– Another example of abstraction

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2. I/O Control Drivers2. I/O Control Drivers

• An application can use a peripheral device without needing to know the details of the device– Applications can make logical I/O requests without knowing

the details of the physical commands required by the device• Logical request: a generic description of the desired result• Physical command: the specific instructions required by the device to

produce the desired result

APPLICATIONAPPLICATIONAPPLICATIONAPPLICATIONI/OI/O

CONTROLCONTROLDRIVERDRIVER

I/OI/OCONTROLCONTROLDRIVERDRIVER

PERIPHERALPERIPHERALDEVICEDEVICE

PERIPHERALPERIPHERALDEVICEDEVICE

Logical

I/O R

eque

sts

Logical

I/O R

eque

sts

Physical

I/O C

omm

ands

Physical

I/O C

omm

ands

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3. Memory Manager3. Memory Manager

• Remember that the CPU interacts directly only with main memory (RAM)

• All actively running programs, and their data, must reside in main memory– The OS itself occupies some of main memory– Each application and data file must have a separate space in

main memory – they cannot overlap

• The memory manager allocates segments of main memory for each process and data file

• It also attempts to protect the system from accidental memory overlaps– Some operating systems do this better than others

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OS

application

Hard DiskHard Disk

RAM

Main MemoryMain Memory

OS: 3. Memory ManagerOS: 3. Memory Manager

• An example of memory management when using an application to create a data file– Before the computer is turned on

• Volatile main memory is blank• Applications and the OS are stored on auxiliary storage

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3. Memory Manager3. Memory Manager

• An example of memory management when using an application to create a data file:

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4. File Manager4. File Manager

• Data is stored on disks in fragments– These file fragments can be scattered in various places on disk,

organized by the “file allocation table” (FAT)– Keeping track of all this information is a messy job

• But computers are really good at doing this kind of messy job

• The file manager hides that detail– We don’t need to worry about where all the file fragments are– The file manager deals with the all the messy details of how

and where the file is physically stored on disk• The file manager also provides a hierarchical file

structure of folders and subfolders for our use– To get to a file, we only need to know the file name and which

folder (“directory”) it is in

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• User interface is the medium for communication between the user and the computer– Text-based command line interpreters (CLIs)

• Examples: DOS, Unix ‘shell’• Very powerful• Very steep learning curve; very unforgiving

– Graphical user interfaces (GUIs)• Examples: Windows, Macintosh,

Linux windowing systems• Intuitive and user-friendly• Slower and less efficient than CLIs

– Although not a problem with fast computers• Capabilities limited to those anticipated

by GUI designers

5. User Interface5. User Interface

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Personal Computer Operating SystemsPersonal Computer Operating Systems

• Various operating systems are available for personal computers (desktops, laptops, workstations)– Windows (Microsoft)

– Macintosh (Apple)• Mac OS X is built on Unix

– Linux (open source – distributed development)• Linux is a kind of Unix

• Hand-held devices– Palm Pilot (Palm OS)

– Pocket PC (Windows Mobile)

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Development of UnixDevelopment of Unix

• Unix is a generic term for a very common operating system for small-to-midsize multi-user computers

• Initially developed at AT&T Bell Labs in New Jersey– First version operational 1971

• Additional development at UC Berkeley (1970’s)• Adopted by most manufacturers of minicomputers

in the 1980’s– Each manufacturer made their own proprietary version of

Unix

• Adapted to PCs by hobbyists in the 1980’s (Minix)

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• 1991: Linus Torvalds (undergraduate student at Helsinki Univ., Finland) decided to write a new OS and sent out the following message:

Hello everybody out there using minix – I’m doing a (free) operating system (just a hobby, won’t be big and professional like gnu) for 386(486) AT clones.

• Linus called it Linux• Thousands of people around the world have joined in to

build a full-featured, professional, free operating system– Coordination through the web (www.linux.org)

LinuxLinux

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LinuxLinux

• Linux is free (or cheap)• It is open source, meaning that the

source code is available to anyone– Errors and problems can be solved quickly– New features can be added easily– Linux can be adapted to individual circumstances– Licensed using the GPL (General Public License)

• Linux is becoming more and more common as a personal computer OS– Some WFU students and faculty have it on their laptops– Competition for Microsoft Windows

Whazzup with the Penguin,

anyway?

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• Widely used on large Web servers• As of 10/07, of 142,800,000 Web sites surveyed, ~50% are running Linux

– (Apache is the Linux program that runs Web servers)

LinuxLinux

http://news.netcraft.com/archives/web_server_survey.html

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• Widely used in large computational clusters– More powerful than a traditional supercomputer at a fraction of the cost– Example: www.deac.wfu.edu

• ~300 processors in one cluster– Other large clusters (many Linux) listed at

www.top500.org

LinuxLinux

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Open Source SoftwareOpen Source Software

• Open source claims the promise of– Better quality– Higher reliability– More flexibility– Lower cost– Avoiding ‘lock-in’ to the products of a specific vendor

• Proprietary software depends on the profit motive – but what motivates those who create open-source software?– Selfless benevolence? Ego?

• Open source software has potential security issues– Having all details of the source code available might allow

hackers to exploit weaknesses

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Who Are These People?Who Are These People?

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Who Are These People?Who Are These People?

Just a minor traffic violation, apparently…

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MicrosoftMicrosoft

• Founded in 1975 by Bill Gates and Paul Allen– Both college dropouts

– Now very rich (together worth >$72,000,000,000)

• Paul Allen– World’s 6th richest person

– Owns Seattle Seahawks and Portland Trailblazers

– Has a 414-foot yacht Octopus equipped with 2 helicopters and a 60-foot submarine

– Financial backer of Space Ship One – the first private craft to make it into space

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Space Ship OneSpace Ship One

• Financed by Paul Allen

• Successful trip Fall ‘04

• Won $10 million prize– For only a $40 million

investment!

• Richard Branson has licensed Space Ship One to create Virgin Galactic– ‘Space’ trips for $200,000 by 2009…

– New Mexico is building a$20,000,000 spaceport

• Now Google is sponsoring a $30 million competition for a private lunar lander

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Basic Office ApplicationsBasic Office Applications

• Word Processing• Spreadsheets• Presentations• Databases• Personal information

management– Email– Contacts– Calendar– ToDo lists

• Etc.

• Microsoft Office (~$500)– Word – word processing– Excel – spreadsheet– Access – database– PowerPoint – presentations – Outlook – personal information

• WordPerfect Office• Lotus SmartSuite• OpenOffice.org (open source—free)

– Writer – word processing– Calc – spreadsheet– Base – database– Impress – presentations– Windows, Macintosh, Linux, etc.

• Etc.

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Productivity SoftwareProductivity Software

• For years, locally installed office productivity apps have been a major use of PCs• Google has been expanding into areas formerly available only through locally

installed apps– Not just conventional Internet-based uses, such as

• Email (Gmail) & IM (Talk)• Blogging• Web site creation

– But they’ve recently been adding more office productivity tools• Word processor• Spreadsheet• Calendar• Calculator• Drawing• Photo and video tools

– All Web-based and free (ad-supported)– Opportunities for collaborative document creation– But, must be online to use Web-based software

• Does this help explain why Google is getting in to the WiFi business?

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Productivity SoftwareProductivity Software

• Is Google trying supplant or complement Office tools?– Google has been hiring away high-level talent from Microsoft– Google may be in a position to transform computing from local applications to

Internet applications– Microsoft’s ‘.Net’ and ‘Live’ have tried to go there,

but aren’t having a lot of success

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Productivity SoftwareProductivity Software

• Google is also trying to get involved more in social networking activities– orkut.com, Facebook, MySpace– IM, blogging, chat rooms, etc.– Google Video– YouTube purchase last fall

• $1.65 Billion for Chad Hurley and Steve Chen

• Company started in a garage in 2/05– Originally featured videos of

one of the founders’ cats• Gives Google another avenue for

putting ads in front of people• But, what about copyrighted material?

– Billion dollar lawsuit filed last Spring…

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Web 2.0Web 2.0

• The shift from the Web as a publications medium to the Web as a platform for expression– An architecture of participation– Web-based applications– User-generated content

• A very cool 4-minute video about what it all might mean:– http://www.youtube.com/watch?v=NLlGopyXT_g

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Intellectual PropertyIntellectual Property

• Intellectual property– Something intangible that can be owned– A creative expression of ideas

• Like any property, intellectual property needs protection• Different types of intellectual property have different

legal protections– Trademarks protect words, names, symbols, colors and smells

used to identify goods– Patents protect inventions – devices or processes – but not ideas– Keeping trade secrets is a legally sanctioned way to protect

information without disclosing it publicly– Copyrights protect creative expressions of thoughts and ideas

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Patent and Copyright LawPatent and Copyright Law

• Federal patent and copyright laws authorized by the Constitution – (Article I, Section 8)

– “To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries”

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PatentsPatents

• Patents are awarded for discoveries or inventions that “promote the Progress of Science and Useful arts”– The discovery or invention must be novel and non-obvious– Usually valid for 20 years from application date, non-renewable

• Computer programs were formerly ineligible for patents– Were considered to be just a mathematical algorithm or

calculation, not an invention, and therefore not patentable• As of mid-1990’s, some software may now be patented

– A rather controversial situation• GIF images were for a time charged royalties due to a patent on the LZW

 compression algorithm, which expired in 2003

• Software is more commonly protected by copyright rather than patent

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Software PatentsSoftware Patents

• Recent issues over patents on software and algorithms– NTP, Inc. vs. Research in Motion Ltd.

• NTP holds a 1995 patent on accessing email through a wireless device• RIM’s BlackBerry device was found to infringe that patent• Settled last spring for $612.5 million

– Acacia Research Corp. vs. any and all digital media • ARC holds a 1992 patent on

“any type of content (audio, video) that is digitized with some kind of compression, then stored on a server, with retrieval through satellite, phone lines or Internet, with playback on a PC”

• Demanded royalties first from members of the adult entertainment industry (presumably an easy target?)

• Have received payments from many, including Bloomberg, Disney, Playboy and Virgin

• They just announced acquisition of a patent on the idea of a projector