CS 170: Computer Applications for Business

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CS 170 Computer Applications for Business

• Course Wesbite http//remus.rutgers.edu/goelz/c
  s170/
• Instructor
• Shefali Pandey

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Lecture 2

• Questions about recitation sections/ locations
• Know your computer, Know your IT
• Human-Computer Interface, Using it
• Networked World Internet, Ethernet

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Knowing your Computer

• PC and MACs
• Monolithic package(laptop)
• Assorted components (regular desktop).

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Display

• Monitor bit-mapped display
• Bulkier CRT (Cathode Ray Tube)
• Slimmer LCD (Liquid Crystal Display)
• Color display RGB (Red Green Blue)
• Pixel Picture Element, unit of division on
  computer screen, higher pixel count sharper
  image

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The works

• Motherboard
• Microprocessor
• Memory

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Motherboard printed circuit board
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Microprocessor - the brains

• Instructions per second or Mega Hertz
• Pentium II 233 Mhz
• Pentium III 450 Mhz
• Pentium IV 1.5 Ghz!!

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Memory

• RAM 512 MB or 1 GB (standard), volatile,
  quicker
• Hard disk 40 GB to 160 GB (standard)
• permanent

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Hardware Vs Software

• Hardware wires, circuit, tangibles
• Software Program, logic, intangible
• Software cheaper and easier to fix

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Terminology

• Algorithms
• Program
• Run / Execute
• Boot
• Reboot / Restart
• GUI (Graphical User Interface)

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Abstraction

• Generalization
• 2 3 5
• 4 5 9
• Use the same concept of addition to add
• Any two numbers a b c
• Useful in GUI - Browsers, Paint applications,
  Windows based OS.

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Easy help

• www.howstuffworks.com
• www.wikipedia.com

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Abstraction in GUI

• File New Open Save Print Exit
• Edit Select Copy Cut Paste Find
• View
• Insert
• Format
• Tools
• Help

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To learn new software

• Click Around
• Blaze Away
• Watch
• Think and question.

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The Networked World

• Remote no more
• Interconnected
• Changing Interactions
• English language of the world
• Internet becoming language of business and
  communication
• Freedom of speech

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Communication

• Always between two or more entities
• Synchronous Sender Receiver
• Active at the same time
• Eg. Telephone, face to face.
• Asynchronous Sender Receiver
• Active at different times
• Eg. Email, Good ol mail

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communication continued

• Broadcast
• 1 Sender Many receivers (everyone)
• Eg. Yahoo website, free to air radio
• Multicast
• 1 Sender Many receivers (select few)
• Eg. Group chat, Paid cable
• Point to Point
• 1 sender 1 receiver
• Eg. Instant messaging, telephone.

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Client Server Interactions

• Client (you) requests service
• Server (Gmail/Yahoo) services request

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The Internet

• Collection of computer connected via n/w
• Each machine unique IP address
• Eg. 0.0.0.0
• 1.0.0.0
• 2.1.1.1
• 255.255.255.255
• Numbers range from 0-255

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• Domain Name System (DNS) Makes IP addresses
  readable / easier to remember
• Domain Related group of computers
• Hierarchy
• Eg. cs.rutgers.edu
• search.rutgers.edu

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• Edu rutgers.edu
• Org wikipedia.org
• Com google.com
• Gov www.usa.gov
• Country specific -- .us .uk .in .fr

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Domain Name System

• Client Server Interaction
• Client ? Nearest DNS server
• DNS server ? Root Server
• Root Server ? Authoritative Server
• Each server shall have a mapping of IP addresses
  to corresponding domain names, the level of
  detail differs.

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Sending messages

• TCP/IP
• Transmission Control Protocol/Internet Protocol
• IP Packets
• At SOURCE - single mssg may be broken into a
  number of IP packets
• Each shall follow TCP/IP protocol to reach
  destination INDEPENDENT of each other
• At RECEIVER packets combine to create
  original message.

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Important points

• Packets travel independent of each other
• For this packets have information like
  destination address and sequence number (in
  original mssg)
• Routers
• Hops

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Networks

• WAN Wide Area Networks
• Eg. Across cities and countries
• LAN Local Area Networks
• Eg. Across an office building, computer lab
• LANs use ETHERNET technology

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Ethernet

• Ether, wire, optical fiber - any channel
• Mssg broadcast to all computers
• Decentralized
• Each computer hears the channel, if no noise
  broadcasts mssg (talks)
• At a time only one computer talks, others
  listen and wait for their channel to grow
  quiet.

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Ethernet
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Connecting to the Net

• ISP Internet Service Provider
• Organization wide LAN
• Wireless

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Versus

• World Wide Web Collection of web servers and
  files (uses HTTP)
• Internet Wires Routers (uses TCP/IP)
• http//remus.rutgers.edu/goelz/cs170
• protocol
• Server name
• Pathname of file on server

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Next LectureDisplaying information on the web

• HTML
• Search Engines
• Chapters 4 5 6