Chapter 6 - Basic Communication

Introduction
Communication Using Electricity
Signals On Wires
Information Coding
MODEM: A Modulator and a Demodulator A modem is a device needed for communication across a dial-up telephone connection or for long distance communication across a wire. A modem supports two-way communication because it contains a modulator for the signal being sent and a demodulator for the signal being received.
Modems Allow Two-Way Traffic
A Character Code For Digital Information - ASCII, EBCDIC, UNICODE
Detecting Errors
When using electrical signals to communicate digital information, electrical or magnetic interference can cause the value of one or more bits to be changed
Adding a parity bit to each character code before transmission can help the hardware detect errors that occur when transmitting the character across a network. However, parity alone is not sufficient to detect all possible errors; more powerful techniques are needed[Hamming codes]