Computer – Data Communication and Network

Some Basic Facts

·         Signals are electric or electromagnetic encoding of data and signaling is propagation of signal along suitable communication medium.

·         Transmission is communication of data achieved by the propagation andprocessing of signals.

·         In parallel data transmission, each wire carries a bit of information.

·         In series data transmission, each bet is sent sequentially one after another and it is slower than that of parallel transmission.

·         In synchronous transmission, characters are transmitted as groups, with control characters in the beginning and at the end of the bit train.

·         In a synchronous transmission, each character is transmitted separately.

·         In simplex mode of communication, channel is used in one direction.

·         In half duplex mode of communication, channel is used in both directions.

·         In full duplex mode, the communication channel is used both directions at the same time.

 Computers are connected with each other for communication creating the computer network. Computer network is of three types:

1. Local Area Network (LAN)
2. Metropolitan Area Network (MAN)
3. Wide Area Network (WAN)

Local Area Network (LAN)  It is a data communication network, which connects many computers of workstations and permits exchange of data and information among themselves, within a localized area.

Metropolitan Area Network (MAN) It is a network of computers of a large region. For example, all the branched of an electric department of a city and the network of computers of all the offices.

Wide Area Network (WAN)  It is a network linking separate geographical locations. Internet is the best example of it.