Computer Networks and Components

Definition

• A computer network is a number of computers linked together to enable them to share computing resources.
• Networks can be permanent (via cables) or temporary (via modem)
• The sharing of resources through a network can also be local or global
• Networks allow different types of computers to communicate.

Benefits

• Information can be accessed in remote areas that is part of the network
• Information can be shared easily
• Information generated by a single user can be shared world-wide instantaneously.
• Networks can maintain a single file without copying entire file to computer.
• Resources can be shared easily
• One shared file rather than many separate files
• Physical resources can also be shared (e.g. printer)
• Transferring signals on a network
• To transfer information on a network, we need to consider three areas.
  • Hardware needed to transmit information over the network
  • Most cost-effective method to transmit and receive the signals
  • An standard to code and decode signals (e.g. ASCII)

Analog Transmission

• An analog signal is a continuous wave that reflects variation.
• a telephone mainly uses analog signals for local distribution
• Digital Transmission
• A digital signal is in binary format (i.e. 1’s and 0’s)
• Digital lines are faster and more accurate
• Can handle text, graphics, voice, video at high speeds.
• HIGH cost!
• Modem (MOdulator/DEModulator)
• Many computers are connected to the internet via a phone line. However:
• Computers are digital
• Phone lines are analog
• Modems provide a link between digital computers and analog phone lines.
• Modems convert:
• digital signals to analog signals (modulation)
• Analog signals to digital signals (demodulation)