Change Catalysts Slide 1- 2 - Computer Science

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Chapter 1

Catalysts for Change

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Change Catalysts

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Organization of Chapter


Introduction


Milestones in computing


Milestones in networking


Milestones in information storage and retrieval


Information technology issues


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Information Age


Definition


Unprecedented access to information


Examples


Cell phones


Email


World Wide Web


Catalysts


Low
-
cost computers


High
-
speed communication networks

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Technology and Values


Dynamic between people, technology


People adopt technology


Technology changes society


Effects of technology use


Positive examples


Negative examples


Ultimately, people in control


Decide whether to adopt technology


Influence rate of technological progress

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Milestones in Computing


Mechanical machines (1600s

1800s)


Boolean algebra (1850s)


Electronic switching circuits (1930s)


Early computers (1940s)


Commercial computers (1950s


)


Transistor (~1950)


Integrated circuit (~1960)


Microprocessor (~1970)


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Mechanical Computing Machines


Arithmetic Machine (Pascal, 1640)


Add, subtract whole numbers


Step Reckoner (von Leibniz, late 1600s)


Multiply, divide through repeated addition, subtraction


Difference Engine prototype (Babbage, 1822)


Compute polynomials through repeated addition


Applications to logarithmic and trigonometric functions


Difference Engine (Babbage, 1820s
-
1830s)


Never completed by Babbage


Later implementations validated design


Lego implementation

and description
(accessed 31 Jan 08)

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Analytical Engine


Designed by Charles Babbage


Compute mathematical formulas through
repeated addition, subtraction


No instruction set


No conditional execution of instructions


No notion of memory addressing


Never constructed


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Ada Byron


Daughter of poet Lord Byron


Received mathematical training


Engaged in extensive correspondence with
Charles Babbage


Predicted future uses of computing machines


Described how to compute Bernoulli numbers on
Analytical Engine


Sometimes called “first programmer”

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Boolean Algebra


George Boole (1815
-
1864)


Lower
-
class English background


Became math professor in Ireland


Boolean algebra


Formalized logical reasoning


Rules for manipulating two symbols: true, false


Claude Shannon


Ph.D. student at M.I.T. in 1930s


Built switching circuits performing boolean functions
(AND, OR, NOT, etc.)

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Z Series


Konrad Zuse (1910
-
1995)


German construction engineer


Background in aviation industry


Z1, Z2, Z3 computers


Mechanical and electro
-
mechanical computers


External programs (punched 35 mm film)


No branch or jump instructions


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Harvard Mark I


Howard Aiken (1900
-
1973)


IBM sponsored project


Computer built from IBM products


Punched card readers/writers


Electronic typewriters


73 IBM Automatic Accounting Machines


Programs stored externally on paper tape

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Colossus


Code
-
breaking machine


Created at England’s Bletchley Park during World
War II


Team included Alan Turing (1912
-
1954)


Special
-
purpose electronic computer


Secrecy: little impact on future machines

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Atanasoff
-
Berry Computer


Built at Iowa State College (1939
-
1941)


Professor John Atanasoff (1903
-
1995)


Grad student Clifford Berry (1918
-
1963)


Solved systems of linear equations


Built with vacuum tubes


Used rotating drum for random
-
access memory


Stimulated work of Eckert and Mauchley

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ENIAC


Built at University of Pennsylvania during World
War II, completed 1946


Prof. John Mauchley (1907
-
1980)


J. Presper Eckert (1919
-
1995)


General
-
purpose programmable computer


Completely electronic internals


Program “wired in” from outside


not stored in
memory

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Small
-
Scale Experimental Machine


Built at University of Manchester (England)


F. C. Williams (1911
-
1977)


Tom Kilburn (1921
-
2001)


Fully electronic operation


Random
-
access memory in CRT


Programs and data stored in memory


Jump instruction

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Commercial Computers


Ferranti Mark 1


Introduced February 1951


Based on U. Manchester computer


Remington Rand UNIVAC


Delivered March 1951


Based on ENIAC


Predicted outcome of 1952 Presidential
election


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Transistor


Replacement for vacuum tube


Invented at Bell Labs (1948)


Semiconductor


Faster


Cheaper


More reliable


More energy
-
efficient

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Integrated Circuit


Semiconductor containing transistors, capacitors,
and resistors


Invented at Fairchild Semiconductor and Texas
Instruments


Advantages over parts they replaced


Smaller


Faster


More reliable


Less expensive

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IBM System/360


Before System/360


IBM dominated mainframe marked in 1960s


IBM computers were incompatible


Switch computers


rewrite programs


System/360


Series of 19 computers with varying levels of
power


All computers could run same programs


Upgrade without rewriting programs

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Microprocessor


Computer inside a single semiconductor chip


Invented in 1970 at Intel


Made personal computers practical

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Personal Computers


Hobby computers


Mark
-
8 (1974)


Altair 8800 (1975)


Commercial PCs (personal computers)


Tandy (TRS
-
80)


Apple (Apple I, II)


Business PCs


Spreadsheet program (VisiCalc, 1979)


IBM PC (1981)

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Milestones in Networking (1/2)


Electromagnetism (early 1800s)


Telegraph (1844)


Telephone (1876)


Typewriter and teletype (1873, 1908)


Radio (1895)


Television (1927)

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Milestones in Networking (2/2)


Remote computing (1940)


ARPANET (1969)


Email (1972)


Internet (1983)


NSFNET


Broadband

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Electricity and Electromagnetism


Volta invents battery (1799)


Oersted shows electricity creates magnetic field
(1820)


Sturgeon constructs electromagnet (1825)


Henry uses electromagnetism to communicate
(1830)


Decew

Generating Station

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Telegraph (1844)


U.S. government funded first line


40 miles from Washington, D.C. to Baltimore


Built by Samuel Morse in 1843
-
1844


Private networks flourished


12,000 miles of lines in 1850


Transcontinental line in 1861


200,000 miles of lines by 1877


Technology proved versatile


Fire alarm boxes


Police call boxes


Western Union Telegram’s Demise, end January 2006 in
US
.
Canada
’s still lives!
Enhanced US Service


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Telephone (1876)


Alexander Graham Bell (1847
-
1922)


Constructed harmonic telegraph


Leveraged concept into first telephone


Social impact of telephone


Blurred public life / private life boundary


Eroded traditional social hierarchies


Reduced privacy


Enabled first “online” communities


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Typewriter and Teletype


Typewriter (1873)


Individual production of “type set” documents


Common in offices by 1890s


Teletype (1908)


Typewriter connected to telegraph line


Popular uses


Transmitting news stories


Sending records of stock transactions



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Radio (1895)


Pioneers


Hertz creates electromagnetic waves


Marconi invents radio


First used in business


Wireless telegraph


Transmit voices


Entertainment uses


Suggested by Sarnoff


Important entertainment medium by 1930s

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Television (1927)


Became popular in 1950s


Price fell dramatically


Number of stations increased


Social effects


Worldwide audiences


Networks strive to be first to deliver news


Impact of incorrect information; e.g., 2000
presidential election

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Remote Computing (1940)


Stibitz and Williams build Complex Number
Calculator at Bell Labs


Bell Labs part of AT&T (phone company)


Teletype chosen for input/output


Allows operator to be distant from machine


Long
-
distance demonstration between New
Hampshire and New York City


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ARPANET (1969)


DoD creates ARPA in late 1950s


Licklider conceives of “Galactic Network”


Decentralized design to improve survivability


Packet
-
switching replaces circuit switching

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Email (1972)


Creation


Tomlinson at BBN writes software to send,
receive email messages


Roberts creates email utility


Current status


One of world’s most important communication
technologies


Billions of messages sent in U.S. every day

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Internet (1983)


Kahn conceives of open architecture networking


Cerf and Kahn design TCP/IP protocol


Internet: network of networks communicating
using TCP/IP

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NSFNET


Created by National Science Foundation


Provided access grants to universities


Encouraged commercial subscribers for regional
networks


Banned commercial traffic on NSFNET Backbone


Private companies developed long
-
distance
Internet connections


After private networks established, NSF shut
down NSFNET Backbone

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Broadband


Broadband


High
-
speed Internet connection


At least 10x faster than dial
-
up connection


South Korea


World leader in broadband networking


Three
-
quarters of homes have broadband
connections


Undersea Cables

(broken by ship, January 2008)

(More
maps
)

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Milestones in Information Storage

and Retrieval


Codex


Gutenberg’s Printing Press


Newspapers


Hypertext


Personal Computers


Single
-
Computer Hypertext Systems


World Wide Web


Search Engines

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Codex


Rectangular pages sewn together on one side


Replaced papyrus scrolls as way of storing
books


Advantages of codex over scroll


More durable


Allows quicker access to particular passages


Manufacturing technologies


Copying by hand


Wood engraving

Codex

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Gutenberg’s Printing Press


Based on movable metal type


Church principal customer of early publishers


Powerful mass communication tool


Printing press’s impact on Reformation


More than 300,000 copies of Luther’s
publications


Protestants out
-
published Catholics by

10
-
to
-
1 in the middle 16
th

century

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Newspapers


Newspapers: Stimulated free expression


Governments responded


Licensing


Censorship


Impact on American Revolution


Newspapers helped unify colonies


Swayed public opinion toward independence


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Hypertext


Vannevar Bush envisions
Memex

(1945)


Ted Nelson


Coined word hypertext


Proposed creation of Xanadu (1967)


Douglas Engelbart


Directed construction of NLS (oNLine System)


Demonstrated windows, email, mouse,
videoconferencing (1968)

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Personal Computers


Xerox PARC (Palo Alto Research Center)


Alan Kay’s Alto had CRT monitor, keyboard,
and mouse


Ethernet


Apple Computer


Steve Jobs and Steve Wozniak


Macintosh (1984)


Microsoft Windows (1990) quickly became
dominant graphical user interface


Now
one computer

to rule them all!

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Single
-
Computer Hypertext Systems


Peter Brown at University of Kent


Guide (1982)


Released versions for Macintosh and IBM PC


Apple Computer


HyperCard (1987)


Hypertext system based on “stacks” of “cards”


Links represented by buttons


Basis for best
-
selling games Myst and Riven

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World Wide Web


First browser built at CERN in Switzerland


Tim Berners
-
Lee: WorldWideWeb (1990)


Berners
-
Lee created Web protocols


Protocols based on TCP/IP


general


Later browsers


Mosaic


Netscape Navigator


Netscape Mozilla


Microsoft Internet Explorer (most popular)


Mozilla’s Firefox, Opera, …

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Search Engines


Crawler
-
based engines (Google, AltaVista)


Programs called spiders follow hyperlinks and
visit millions of Web pages


System automatically constructs Web page
database


Human
-
assisted engines (Open Directory)


Human
-
built Web page database (
dmoz.org
)


Web page summaries more accurate


Far fewer Web pages in database


Hybrid systems (MSN Search), Clusty, …

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Information Technology


Definition: Devices used in creation, storage,
manipulation, dissemination of data, sound,
and/or images


Examples: Computers, telephones, video
cameras


People making greater use of IT


Costs keep falling


Capabilities keep rising

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IT Issues (1/3)


Email


Easy way to keep in touch


Spam has become a real problem


Web


Free access to huge amounts of information


Harmful consequences of some sites


CDs, MP3s


Free or cheap copies readily available


May be unfair to musicians


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IT Issues (2/3)


Credit cards


Convenience over cash and checks


Increases possibility of identity theft


Who owns information about transactions?


Telecommuting


Saves time, allows more flexible work hours


Can lead to longer work hours


May result in fewer chances for promotion


Those
left behind

are more stressed!

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IT Issues (3/3)


Improved global communication network


Allow companies to sell to entire world


Allow companies to move jobs out of U.S.


World Wide Web


A conduit for democratic ideas?


Another tool for totalitarian governments?


935 Lies

quality, factual, biased?

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Conclusions


Revolutionary discoveries are rare


Information technology has long history


Rate of technological change accelerating


Wrong question: “What will the computer do to
us?”


Right question: “What will we make of the
computer?”

(quoting Seymour Papert)