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2002 Prentice Hall
Computer Currents: From Calculation to
Communication
Chapter 1
2002 Prentice Hall 2
Topics
Living without Computers
Computers in Perspective: An Evolving Idea
Computers Today: A Brief Taxonomy
Computer Connections: The Internet Revolution
Living with Computers
Topics
2002 Prentice Hall 3
What would we do without
computers in our personal
and professional
lives?
Living Without Computers
2002 Prentice Hall 4
Information-Processing Machine
Input documents
Processdata
Print materials
2002 Prentice Hall 5
Howard Aiken
John Atanasoff
The scientists and mathematicians who designed and built the first working computers:
The First Real Computers
Konrad Zuse
John Mauchly & J. Presper Eckert
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In 1939, Zuse built the first programmable, general-purpose digital computer.
His computer was built from electric relays to automate engineering calculations.
“I was too lazy to calculate and so I invented the computer.”
Konrad Zuse
2002 Prentice Hall 7
Atanasoff-Berry Computer (ABC)—the first electronic digital computer
Built in 1939, this computer used vacuum tubes and was based on binary arithmetic.
It was never a fully operational product.
John Atanasoff
2002 Prentice Hall 8
Howard Aiken
In 1944, he completed the Mark I, the largest electromechanical calculator ever built.
It was built with electromechanical relays and followed instructions punched in paper tape.
2002 Prentice Hall 9
John Mauchlyand Presper Eckert
In 1945, Mauchly and Eckert built the ENIAC (Electronic Numerical Integrator and Computer).
The ENIAC was built with 18,000 vacuum tubes that failed on an average of once every seven minutes.
After the war, they created the Univac I - the first general-purpose commercial computer.
2002 Prentice Hall 10
Evolution and Acceleration
Hardware changes are defined by generations.
First GenerationVacuum tubes
Second GenerationTransistors
Third GenerationIntegrated circuits
Fourth GenerationMicroprocessor
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First-Generation Computers
1930s – 1940sVacuum tubes used as switchesLarge computersExtremely slow by today’s standardsProne to frequent failureIncludes the ABC, Mark I, ENIAC, UNIVAC,and others of similar design
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Second-Generation Computers
1950s – mid-1960s
Transistors used as switches
Smaller than vacuum-tube-built computers
As much as a thousand times faster than first-generation computers
More reliable and less expensive
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Third-Generation Computers
Late 1960s
Hundreds of transistors packed into a single integrated circuit on a silicon chip
Dramatic reduction in size and cost
Significant increases in reliability, speed, and efficiency
Mass production techniques to manufacture chips inexpensively
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Fourth-Generation Computers
1970s to present
Complete computer on a chip
Radical change in the appearance, capability and availability of computers
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A Brief Taxonomy
Mainframes
Supercomputers
Workstations
Personal Computers
Portable Computers
Embedded Computers
Special-Purpose Computers
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Multi-User Computers
Supercomputers…the fastest, most powerful computers
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Multi-User Computers
Mainframes many users can access computer resources simultaneously
Minicomputerssmaller and less expensive than mainframes
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Single-User Computers
Workstations High-end desktop computer Servers provide software and other resources to computers over a network
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Single-User Computers
Personal Computers (PC)
Dedicated to serving one user
Computing power for word processing, accounting and other common applications
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Portable Computers
Laptop lightweight, battery-operated
computers with flat screens,
Hand-held or Palmtop computers designed for
communications and computing
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Special-Purpose Computers
Special-Purpose often attached to sensors to measure and/or control the environment programs etched in silicon so they can’t be altered (firmware)
Embedded enhance consumer goods control a variety of hardware devices, including robots
2002 Prentice Hall 22
Computer Connections: The Network Revolution
Local Area Networks (LAN)– resource sharing allow communication between users (in the
same building or cluster of buildings)
Wide Area Networks (WAN)– resource sharing allow communication between users (across the
country or the world)
“There are three kinds of death…there’s heart death, there’s brain death, and there’s being off the network.”
2002 Prentice Hall 23
The Internet Explosion
A network of networks
World Wide Web for usability
Electronic mail
Multimedia content
Self-publishing
On-line transactions
Intranets
Network computers
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World Wide Web
Web browsers are portals into the Web
Web pages are interlinked documents
Web sites are web pages grouped together
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Electronic Mail (e-mail)
The primary use of the Internet today is for communications: E-mail is easy to use Messaging is quick
“The great success of the Internet is not technical, but its human impact”
Dave Clark
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Explosive Internet Growth
1994? 3 million people connected
Today? Hundreds of millions
The United States leads the world in Internet activity
Approximately 1/3 of U.S. households connected in 1999
By 2003, twice that number is expected to be connected
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Impact of the Internet
Companies are replacing mainframe and PC systems with Intranets
Private intra-organizational networks that allow people to transmit, share and store information
Computers may be used mostly as gateways to intranets and the Internet
These network computers cost less than typical PCs because they contain less hardware and are easier to maintain (software stored on a central server)
2002 Prentice Hall 28
Internet Connections
Direct connection One that’s hard wired through a business, school or
government
Indirect connection Telephone system
Cable TV connection
Wireless connection
2002 Prentice Hall 29
Living with Computers
What do you really need to know about computers?
Understand the basic computer concepts
Learn how to use software applications
Be aware of the social and ethical issues
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Concepts of hardware and software
2002 Prentice Hall 31
Software Applications
Word processing anddesktop publishing
Spreadsheets anddatabases
Computer graphics,multimedia and hypermedia
Telecommunication and networking
Artificial intelligence
General problem-solving
Programming languages
2002 Prentice Hall 32
Threat to personal privacy
Hazards of high-tech crime & keeping data secure
Risks of computer system failures
Social and Ethical Issues
Threat of automation and dehumanization of work
Abuse of information
Over dependence on complex technology
“True computer literacy is not just knowing how to make use of computers and computational ideas. It is knowing when it is appropriate to do so.”
Seymour Papert
2002 Prentice Hall 33
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