katamad

• communications

  Any process that permits the passage from a sender to one or more receiver of information of any nature
• Information


  Knowledge or intelligence
• Data


  Information that is stored in digital form, in any forms that are presented, agreed processed, organized and/or stored by the communicating party
• Types of data


  • Alphabetic
  • Numeric
  • Symbolic
• Forms of data


  • Binary-coded alpha/numeric symbols
  • Microprocessor op-codes
  • Control Codes
  • User Addresses
  • Program Data
  • Data Base Information
• Data communication


  The process of transferring information presented digitally (usually in binary form) between two places, often involving computers or computer peripherals
• Forms of information


  • Analog (e.g. human voice, music)
  • Digital (e.g. binary-coded numbers, alphanumeric codes)
• Invention of the telegraph and development of Morse Code

  1837
• Samuel F.B. Morse


  • Transmitted dots and dashes across a wire using electromechanical introduction to represent binary codes for letters, numbers and punctuation
• First telegraph line established between Baltimore and Washington, D.C.


  1844
• First slow-speed telegraph printer invented


  1849
• Western Union Telegraph Company formed in Rochester, New York


  1850
• Emile Baudot invented a telegraph multiplexer allowing signals from up to six different telegraph machines to be transmitted simultaneously over a single wire


  1874
• Telephone invented by Alexander Graham Bell


  1876
• Bell Laboratories developed the first special computer


  1940
• Remington Rand Corporation built the UNIVAC (Universal Automatic Computer)


  1951
• AT&T operating tariff allowed only equipment furnished by AT&T to be connected to AT&T lines, until the Carterfone decision allowed non-Bell companies to interconnect


  1968
• Internet


  A public data communications network used by millions of people all over the world to exchange business and personal information
• Intranet


  Private data communications networks used by many companies to exchange information, resources and software applications among employees
• World Wide Web (WWW)

  A server-based application that allows users/subscribers to access services, commonly accessed using browsers like Internet Explorer, Mozilla, Firefox and Google Chrome
• General classification of equipment used in data communication

  • DTE - Data Terminals/Terminating Equipment
  • DCE - Data Circuits-Terminating Equipment / Communicating Equipment
• DTE - Data Terminals/Terminating Equipment


  Any binary digital device that generates, transmits, receives, or interprets data messages, where information originates or terminates
• DCE - Data Circuit-Terminating Equipment/ Communicating Equipment


  Any device that transmits or receives data in the form of an analog or digital signal through a network, converting between digital and analog signals
• Network


  A collection of devices connected to each other and able to communicate, where a process in one device can exchange information with a process in another device
• Nodes


  The devices involved in a network that originate, route, and terminate the data
• Five components of data communication

  • Message
  • Sender
  • Receiver
  • Transmission Medium
  • Protocol
• Message


  The information (data) that needs to be transferred, in forms like text, numbers, pictures, audio, and video
• Sender


  The device that sends the data message, e.g. computer, workstation, telephone handset, television
• Receiver


  The device that receives the data message, e.g. computer, workstation, telephone handset, television
• Transmission Medium


  The physical path by which a message travels from sender to receiver, e.g. twisted-pair wire, coaxial cable, fiber-optic cable, radio waves
• Protocol


  A set of rules that govern data communications, representing an agreement between the communicating devices
• Why establish a computer network

  • A collection of computers, printers, routers, switches, and other devices able to communicate over a transmission medium
• Benefits of computer networks

  • Resource sharing
  • Reduced cost and easier installation of software
  • Improved communication
  • Improved flexibility
  • Improved security
• Resource sharing


  Accessing shared resources like files, folders, printers and scanners, increasing productivity
• Reduced cost and easier installation of software


  Purchasing network-based software licenses instead of multiple retail versions
• Improved communication


  Enabling communication over distance through email, instant messaging, video conferencing, social media
• Improved flexibility


  Users can access resources stored on a server from any networked computer
• Improved security


  Shared resources can be secured with access restrictions
• Applications used in networks

  • Web browser
  • FTP
• Improved communication


  Imagine our world without Internet; without e-mail, Instant messaging, video chatting, conferencing social media network sites like facebook and twitter, exchange of information would be very slow. in our world today, distance is not an obstacle on communication.