Accessing information store on World Wide Web ICT Fundamentals 2nd Semester SY 2010-2011 Accessing information store on World Wide Web World Wide Web Servers takes access a step further, providing a hypertext interface. It allows users to view formatted documents on their screen directly, instead of navigating hierarchical menus. Users can access other text, graphic, sound, and movie resources by pointing and clicking highlighted words or pictures, and can download the information being accessed Lesson 16 Fundamentals of Computer Software Lesson 16

Lesson 16 Fundamentals of Computer Software

Lesson 14: Computer Network ICT Fundamentals 2nd Semester SY 2010-2011 Lesson 14: Computer Network Fundamentals of Computer Software Lesson 13 Lesson 13

Communication Media refers to the materials used to transmit data from its source to its destination Twisted-Pair wire - composed of two intertwined copper wires - also called as unshielded twisted-pair (UTP) - also called telephone wire Lesson 13 Fundamentals of Computer Software

Communication Media (cont..) Coaxial Cable commonly known as “coax” widely used in cable TV Two conductors are found: a single piece of wire in the center of the cable a shield that surrounds the first wire with an insulator in between Lesson 13 Fundamentals of Computer Software

Communication Media (cont..) Fiber-Optic Cables More technologically-advanced as compared to the twisted-pair wire and coaxial cable Instead of transmitting frequencies, it transmits pulsating beams of light can carry a greater volume of data Disadvantage: Not flexible and expensive Lesson 13 Fundamentals of Computer Software

Wireless Links Microwave Radio Signals Uses principle of line-of-sight wherein the radio signals travel in a direct line from one repeater station to the next until it reaches its destination Moisture and temperature conditions can make the radio beam bend, resulting in fading Lesson 13 Fundamentals of Computer Software

Wireless Links (cont..) Satellites in Geosynchronous Orbits satellites have made it possible to minimize the line- of-sight limitation placed into orbit and they act like repeater stations Communications satellites often use geosynchronous orbits because they remain stationary above the same location on Earth Lesson 13 Fundamentals of Computer Software

Data Communications Hardware Modem - converts the computer’s digital signals to the telephone’s analog signals and vice-versa - The process of converting digital signals to audio signals is called modulation while the reverse is called demodulation Lesson 13 Fundamentals of Computer Software

Data Communications Hardware Hub A common connection point for devices in a network commonly used to connect segments of a LAN contains multiple ports When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets Lesson 13 Fundamentals of Computer Software

Computer Network a group of interconnected computers which allows computers to communicate with each other and to share resources and information What you can do with Computer Network: play a CD music from one computer while sitting on another computer can burn CDs or make backups on a computer that has one of these but using data from a computer that doesn’t have a CD writer or a backup system can place a movie DVD on the computer that has a DVD player, and then view the movie on a computer that lacks a DVD player Lesson 13 Fundamentals of Computer Software

can connect a printer (or a scanner, or a fax machine) to one computer and let other computers of the network print (or scan, or fax) to that printer (or scanner, or fax machine) can place a CD with pictures on one computer and let other computers access those pictures can create files and store them in one computer, then access those files from the other computer(s) connected to it Lesson 13 Fundamentals of Computer Software

Types of Computer Networks Local Area Network (LAN) refers to computers that are relatively near each other and connected by wires or wireless links It may refer to a network composed of 5 interconnected computers which are located within the confines of a room or it may be composed of 100 interconnected computers which are located in different floors of a building or adjacent buildings Lesson 13 Fundamentals of Computer Software

Types of Computer Networks Wide Area Networks (WANs) a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries composed of several LANs which are distributed over a wider geographic area such as a city, country or even continent One example is the Internet Lesson 13 Fundamentals of Computer Software

Types of Computer Networks Client-Server Relationship One particular computer is used for a specialized task of serving the needs of each node called servers are accessed by the nodes (clients) in order to perform a particular function. each computer still hold (or can still hold) its (or some) resources and files files and resources are centralized Lesson 13 Fundamentals of Computer Software

Types of Computer Networks Peer-to-Peer Relationship The nodes of a network can act as a server, a node, or both. Exchanging files and programs is easy with a peer-to-peer network each computer holds its files and resources. Lesson 13 Fundamentals of Computer Software

Network Topology refers to the physical connection of wires that connect the nodes of the network Four basic types of network topology: Linear Bus Topology the server(s), the nodes and other hardware devices are connected to a single main line Lesson 13 Fundamentals of Computer Software

Star Network Topology the server(s), nodes and other hardware devices are connected to a central hub All messages and data from the source node must first pass through the central hub before it can reach the target node if a hub is broken, the whole network is lost hub Lesson 13 Fundamentals of Computer Software

Ring Network Topology the server(s), the nodes and other hardware devices are connected in a circular chain where each node is connected to the next The last node to be connected is connected to the first node which forms a ring. sent messages will pass through connecting nodes until it reaches the target node. Lesson 13 Fundamentals of Computer Software

Hybrid Network Topology the other types of topologies are combined to form a combination or hybrid network topology usually used to connect different floors or rooms of a building Lesson 13 Fundamentals of Computer Software

Network Protocols applied to networks and data communications refer to a set of rules or standards designed to enable computers connect with one another and to exchange information with as little error as possible Ethernet one of the most widely used network protocol makes use of the linear bus topology, simple and inexpensive Lesson 13 Fundamentals of Computer Software

Token Ring an IBM network protocol which is based on the ring topology a token-ring transmits the electronic address of each node on the network many times per second ARCNET based on the star topology but it has a topology and protocol of its own uses coaxial cable, and the star is perpetuated with hubs attached to the network very slow about 2.5 Mbits per second – but inexpensive, reliable, easy to set up and easy to expand. Lesson 13 Fundamentals of Computer Software