Introduction to the Use of Computers

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Introduction to the Use 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.h
  tml
• Lectures
• 15.1-5.3 Tuesdays 12-14 A320
• Practice sessions
• 22.1-12.3 Tuesdays 16-18 D326
• Exercise
• Exam
• (Resit exam)

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Course Book

• Computer Confluence by George Beekman, 4th
  Edition, Addison Wesley 2001.

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Computer Labs

• Free to use everywhere in CS building if not
  reserved for special purpose or classes
• Linux and Windows
• To change between them, reboot
• From Windows, choose Start, then Reboot
• From Linux, press Ctrl-Alt-Backspace, then
  Ctrl-Alt-Del

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Accounts

• You must have an account to participate in
  practice sessions starting next week!
• If your major is Computer Science
• Contact Pekka Niklander, B425, tel. (09) 191
  44685
• Pekka.Niklander_at_cs.Helsinki.FI
• If not
• First apply for Computer Center account
• Fill the form, bring to your department
• You need both Unix and Windows account
• When you get it, contact Pekka for CS account

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Lecture 1

• The Internet technology and services

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Internet Technologies
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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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Networks Near and Far

• There are two general types of computer networks

LAN(Local Area Network)
WAN(Wide Area Network)
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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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WAN (Wide Area Network)

• A WAN is a network in which the computers are a
  great distance from one another
• Connections are madevia telephone lines,
  satellites, and/ormicrowave relay towers
• Each network site is anode

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WAN (Wide Area Network)

• WANs are often made up of LANs

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Communication á la Modem

• 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

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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 _at_ symbol
• the persons 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 username_at_hostname.su
  b.dom
• username is the persons 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
• gurtov_at_cs.helsinki.fi (Andrei.Gurtov_at_Helsinki.FI
  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 WebBrowsing 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.

Outlook express and Netscape provide more
advanced mail readers
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Disadvantages of Email

• Works only if the recipient responds
• Authentication is not ensured
• Email is not private
• 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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Example of a mailing list

• FOREIGN-STUDENTS_at_HELSINKI.FI is an email list
  meant for distributing information among foreign
  students at the University of Helsinki.
• Instructions on how to USE and LEAVE the mailing
  list are available at the ESN websitehttp//www.
  helsinki.fi/hyy/esn/eng/lists.html
• Before posting mail to the mailing list, be sure
  that you have read the NETIQUETTE of this
  listhttp//www.helsinki.fi/hyy/esn/eng/misc/fs_ne
  tiquette.html

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Mailing list (cont)

• To subscribe mail majordomo_at_helsinki.fi in
  message body subscribe foreign-students
• To unsubscribe mail majordomo_at_helsinki.fi in
  message body unsubscribe foreign-students
• Remember, the machine is stupid so write exactly
  as above and try several times if it fails
• Never send these requests to the mailing list
  itself

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Mailing list (cont)

• Contact the list administrator with related
  problems at foreign-students-owner_at_helsinki.fi
• Do not start or participate in flaming
• I.e. making offensive comments about the person,
  spelling mistakes, etc.
• If you do, the administrator can remove you from
  the list

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Other email features

• Attachments (one MB files are ok)
• Filters
• Ignore sender
• Group by conversation
• Work offline
• Encryption and signature

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News groups

• News (BBS) and web forums are an alternative for
  mailing lists
• Most news groups maintain Frequently Asked
  Questions (FAQ)
• Read FAQ before posting questions
• Web browsers like Netscape and IE have tools for
  reading news

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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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Paging and chatting

• 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
• Microsoft Messenger is a similar tool

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Streaming

• Listen to music from live radio stations
• Using RealPlayer or Microsoft Media Player
• E.g. www.yle.fi provides links to several life
  stations
• You can even find live air traffic control
• Pilots talking to a dispatcher

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File sharing

• Search and download files like latest hits (mp3),
  blockbuster movies (mpeg), latest software
  packages (zip),pictures...
• Make your own files available to others
• Tools like Gnutella or Napster
• Difficult for authorities to snap these systems
  to their distributed nature

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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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E-Commerce

• Users connect (usually for a fee) to a variety of
  on-line databases
• On-line databases include
• current stock market status
• digital libraries
• banking
• shopping

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Online banking

• Provided in Finland by all major banks
• E.g. in Leonia costs less than any other service
  package
• You get a customer number and a PIN code to
  log-in at their web site
• You get a challenge-response table of codes
• All connections are encrypted
• Within the same bank money are moved instantly,
  otherwise it takes a couple of days

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Rules of Thumb On-line Survival Tips

• Protect your privacy
• Cross-check on-lineinformation sources
• Netiquette
• Avoid informationoverload