Introduction to the Use of Computers Andrei Gurtov.

Introduction to the Introduction to the Use of ComputersUse of Computers

Andrei Gurtov

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Course Outline

• Internet• Unix• Word processing• HTML• Spreadsheets• Presentations• Graphics• Peripherals• TeX

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The Course

• Registration: http://ilmo.cs.helsinki.fi/english.html

• Lectures– 16.1-6.3 Tuesdays 12-14 A320

• Practise sessions– 23.1-6.3 Tuesdays 14-16 A215

• Exercise• Exam

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Course Book

Computer Confluence by George Beekman, 3rd Edition, Addison Wesley 1999.

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Computer Labs

• Free to use everywhere in CS building if not reserved for special purpose or classes

• Linux and Windows NT

• Guest account:– login: guest– password: demo

Lecture 1Lecture 1

The Internet: technology and services

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Internet Techologies

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The UNIX Connection

• The Internet has grown out of UNIX Operating System

• Some Internet terms (email address) and services (FTP) become more clear after we cover UNIX

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The Internet: A Network of Networks

The Internet is an interconnected network of thousands of networks linking academic, research, government, and commercial institutions.

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WAN(Wide Area Network)

LAN(Local Area Network)

Networks Near and Far

• There are two general types of computer networks:

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LAN (Local Area Network)

• A LAN is a network in which the computers are physically close to each other– LAN networks are usually set up to share

peripherals, such as printers and network servers

– Each computer andshared peripheral isa node on the LAN

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• A WAN is a network in which the computers are a great distance from one another– Connections are made

via telephone lines, satellites, and/ormicrowave relay towers

– Each network site is anode

WAN (Wide Area Network)

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WAN (Wide Area Network)

• WANs are often made up of LANs

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• A modem is needed to connect a computer to a phone line

• The computercommunicateswith digital signals

• The telephone systemwas designed to transmit voice signals which are analog

Communication á la Modem

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Client/Server Model

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Internet Protocols

TCP/IP (Transmission Control Protocol/Internet Protocol) is the protocol at the heart of the Internet.

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Internet Protocols

• TCP/IP translates into:– TCP (transmission control protocol) breaks

messages into packets.– IP (Internet protocol) is the addressing for

the packets.– computer in the Internet (host) is identified

by IP address (e.g. 128.214.9.225)– IP addresses run out

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Internet Addresses

An Internet address is made up of two parts separated by the @ symbol:

• the person’s user name

• the host name

The host is named using DNS (domain name system), which translates IP addresses into a string of names.

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Internet Addresses

An Internet address includes: [email protected] is the person’s “mailbox”

hostname is the name of the host computer and is followed by one or more domains separated by periods:

• host.subdomain.domain• host.domain• www.cs.helsinki.fi• [email protected] ([email protected] alias)

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Internet Addresses

Top level domains include:

– .edu - educational sites

– .com - commercial sites

– .gov - government sites

– .mil - military sites

– .net - network administration sites

– .org - nonprofit organizations

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Intranets

• Intranets – internal closed networks of organizations that are designed using the same technology as the Internet.

• Firewalls - used to prevent unauthorized communication and secure sensitive internal data.

• Virtual Private Networking (VPN) -- a way to access intranets from public Internet

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Internet Services

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The World Wide Web:Browsing the Web

WWW is a distributed browsing and searching systems developed by CERN.

Use hypertext links and navigational aids to explore information on the Internet.

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Web Addresses

URL (Uniform Resource Locator): addresses for the World Wide Web.

http (hypertext transfer protocol): the protocol of the WWW

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Searching the Web

• A directory (also an index) is a hierarchical catalog of Web sites compiled by researchers.

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Searching the Web

• A search engine offers a more complete database of what is one the WWW. A software robot or spider retrieves the entries according to key word queries.

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Email on the Internet

• Email (one-on-one communication).

• Pine - UNIX-based mail program.

• MIME - Multipurpose Internet Mail Exchange - allows you exchange files through email.

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Disadvantages of Emailand Teleconferencing

• Work only if the recipient responds

• Can be overwhelming (SPAM)

• Both filter out manyhuman componentsof communication

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Mailing Lists and Newsgroups

• Email is a valuable tool for one-to-one communication

• Mailing lists allow you to participate in email discussion groups on special-interest topics.

• Usenet Newsgroups are virtual bulletin boards that you access with a news reader

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Remote Access and File Transfer

The most popular use of the Internet is information discovery and retrieval. Because the Internet is unorganized, you can use the following tools:Telnet: for remote login to other computers.

FTP: file transfer protocol; transfer files from remote computers.

SSH: secure remote login and file transfer

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Real-Time Communication

Talk is a UNIX program that allows you to carry on a split-screen communication

Internet relay chat (IRC) allows several users to type simultaneously

ICQ (I seek you): user-friendly messaging system

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Real-Time Communication

Video telephony (see, hear, and type to another person).

• MBONE - Multicast Backbone – centralized distribution

• NetMeeting – works over ”off-the-shelf” Internet

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• Electronic databases allow users to connect (usually for a fee) to a variety of on-line databases

• On-line databases include:– current stock market status– digital libraries– medical references

On-line Databases

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Rules of Thumb: On-line Survival Tips

• Protect your privacy

• Cross-check on-lineinformation sources

• Netiquettee

• Avoid informationoverload