Thursday, 22 March 2012

Week three- Networking

 Today is week 3 of the class and today we learn about networking. ^^

Computer network is:
- A collection of computers and other hardware devices that are   connected together to share hardware, software, and data as well as to communicate with one another.

A basic network connects 2 computer together by a cable to exchange data and information  while a LAN, allows the sharing of data and devices such as modems and printer.

–Types of LAN based on geographic coverage.
LAN – Local Area Network
WAN - Wide Area Network
MAN - Metropolitan Area Network

computer network can be categorized according to three properties:
  1. typology
  2. protocol
  3. architecture  

Network topology is the layout pattern of interconnections of the various elements (links, notes) of a computer network. It is the geometrical arrangement of the network. The picture below show the different arrangement of the network.

 network protocol defines rules and conventions for communication between network devices. 

The most common network protocols are:
  1. Ethernet
  2. Local Talk
  3. Token Ring
  4. FDDI
  5. ATM
The follow is some common-used network symbols to draw different kinds of network protocols.

Types of Network Protocols

A network architecture is the specification of design principles (including data formats and procedures) for creating a network configuration of data processors. Two most common network are peer- to- peer and server/client network 


There are two types of transmission media; bounded and unbounded. 

     • Bounded Media         • Unbounded Media (air or a vacuum)
- Twisted pair wire        - AM and FM radio
- Co-axial cable             - TV broadcasting
- Fiber optic cables        - Satellite communication
- Microwave radio
- Infrared signals 

- Below are some examples of network electronic device and
their properties:

  • A network bridge connects multiple network segments.A bridge uses a forwarding database to send frames across network segments.

  •  hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment.

  • gateway is used to interfaced with other network.A gateway is a network point that acts as an entrance to another network.

As usual, please enjoy the video regarding computer networking:

Wednesday, 7 March 2012

Week two- Data Communication

Today is week 2 of the class and today we learn about data communication. ^^

It is basically define as

  • collection and distribution of electronic information to and from remote facilities by means of electrical transmission system.   
Some of the communication devises include telephones lines,  satellites or  coaxial cable

Information need to be converted into signal understood by the media so that data can be transmitted. There are 2 types of signal : Analog vs Digital

Analog signal needs to be converted to digital signal of binary digit 0 and 1 as it is the language of computer. This process is called modulation while the reverse is called demodulation 

Binary digit is the smallest unit of measurement in digital and it consist of 0 and 1.

  • 8 bits = 1 byte
  • 1024 /1000 bytes = 1 kilobyte 
  • 1000 kilobytes = 1 megabyte
  • 1000 megabytes= 1 gigabyte

Parallel transmission is the transfer of data simultaneously while in series transmission, each bits is transfer after one another using the same line. For this reason, it is slower than parallel transmission.    

There are three types of data flow ; Simplex, Half - Duplex and Full Duplex


  • transmission in one direction only
  • no interaction between both receiver and transmitter as their role is fixed   
  • etc: TV, radio

Half- Duplex

  • Message can flow in 2 direction but never at the same time
  • One station transmit info to another without interruption and the other station will respond after the transmission is complete.
  • etc: Walkie- talkie

Full- Duplex

  • Both station can transmit and receive signal at the same time. It is the most interactive way of communication among the three.
  • etc: telephone line, tele- conference 

well, i guess this is all from me for time being. Below is a video for you all to enjoy. Thank you and peace to the world ^^.