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of Utah

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Grosch’s Law

• Herb Grosch (IBM, 1950)• A large computer that costs 2X more than

a small computer is...- 2X faster?

University

of Utah

22

Grosch’s Law

• Herb Grosch (IBM, 1950)• A large computer that costs 2X more than

a small computer is...- 2X faster?- 4X faster!

University

of Utah

33

Grosch’s Law

• Why?- Core memory is cheap- Support circuitry is expensive

University

of Utah

44

Grosch’s Law

• Why?- Core memory is cheap- Support circuitry is expensive- No good way to connect machines together

University

of Utah

55

Grosch’s Law Falters

• Chip-based memory- Faster, less wiring...

University

of Utah

66

Grosch’s Law “Repealed”

• Ethernet!- Finally, a way to link cheap machines

together effectively

University

of Utah

77

Ethernet

• Yet another Xerox PARC invention (1973)• Bob Metcalfe and David Boggs• Xerox wanted to network its Alto

computers together

University

of Utah

88

Ethernet

• Inspirations- Data General “star” network

no!- ALOHAnet

yes!

University

of Utah

99

Ethernet

• Basic idea- Shared coaxial cable connecting all

computers- Collision detection- Random backoff

University

of Utah

1010

Ethernet

• Standardization (1979)- DEC, Intel, Xerox agree to use Ethernet- ...but not IBM...

University

of Utah

1111

Ethernet

• Becomes common standard for workstation LANs (local area networks)

• But not for PCs (yet)

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of Utah

1212

Internet

• Descended from ARPANET• A network of many smaller networks

- Glued together by TCP/IP

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of Utah

1313

Internet

• Why?- Technical reasons:

ARPA adopts BSD and TCP/IP in 1980 Rise of LANs

- Social reasons: ARPA (1970s) National Science Foundation (1980s) InterNIC (1992)

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of Utah

1414

Internet

• What?- NOT the World Wide Web (yet)

University

of Utah

1515

Internet

• What?- NOT the World Wide Web (yet)- Telnet

University

of Utah

1616

Internet

• What?- NOT the World Wide Web (yet)- Telnet- FTP

University

of Utah

1717

Internet

• What?- NOT the World Wide Web (yet)- Telnet- FTP- Email

University

of Utah

1818

Internet

• What?- NOT the World Wide Web (yet)- Telnet- FTP- Email- BBS

University

of Utah

1919

Internet

• What?- NOT the World Wide Web (yet)- Telnet- FTP- Email- BBS- Usenet (newsgroups)

University

of Utah

2020

Internet

• What?- Gopher (1991)- Menu-based information retrieval system

University

of Utah

2121

Gopher Demo

University

of Utah

2222

World Wide Web

• Tim Berners-Lee (1990)• CERN

- particle physics laboratory between Switzerland and France

http://en.wikipedia.org/wiki/Image:Tim_Berners-Lee.jpg

University

of Utah

2323

World Wide Web

• First web browser- “WorldWideWeb”

• First web server- “httpd”- Implemented on a NeXT computer

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of Utah

2424

World Wide Web

http://en.wikipedia.org/wiki/Image:First_Web_Server.jpg

University

of Utah

2525

First-ever web page!

• Want to see it?

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of Utah

2626

Break Time

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of Utah

2727

“Test Question”

• On a scrap of paper, write a question that encapsulates one of the points from today's class, and turn it in.

• (Put your name on it!)