Unit 1
Communication and Networking

Network - two or more computers linked together in order to share resources e.g. software, hardware, data, information

Data communication - sending and receiving data from one computer or data processing device to another

Serial transmission
Parallel transmission

Baud rate - (in bits per second) -> speed at which data is transmitted serially

Framing bits - (start, stop, error detection) are transmitted with each character

Bandwidth - the range of frequencies that can be sent / received (measured in Hz)

Synchronous transmission
Asynchronous transmission

Handshaking - exchange of signals between devices to establish their readiness to send / receive data

Modem (MOdulator DEModulator)
ISDN (Integrated Services Digital Network)

Data compression - repeated bytes only sent once with count of repetitions

LAN -> 1 building / site (up to 2 km)


Twisted pair (copper cable) -> telephone line (analogue)

Fibre optic (digital)

Coaxial - insulated so that signals carried don't affect nearby components

Communication satellite - use satellites in geosynchronous orbit

Public lines - dial-up networking

Leased lines - fixed annual fee

WWW is a facility of the Internet -> series of web sites / pages which contain information and are held on host computers

Internet -> worldwide collection of networks

http / ftp / localhost -> protocol used for connection to server

Domain name -> name of server on which Web resource is held

IP address -> unique address of home page e.g. 177.234.443.968

The domain name system maps the domain name onto the IP address