Input / Output Devices (Modem)

Input / Output Devices

Some devices fulfill both input and output functions for a computer system. They act as an interface for data going in as well as out and sometimes they do this simultaneously. One such device is the modem.

Modem

The modem is used to connect the computer to the telephone line. The telephone network operates using analogue voice signals, while a computer operates on digital signals. The modem is the bridge between the digital and the analog signals, and therefore provides an interface between computer and telephone systems.

The modem converts on and off digital data into an analogue signal by varying, or modulating, the phase and frequency of an electronic wave. On the receiving end of a phone connection, a modem does just the opposite: it demodulates the analogue signals back into the digital code. These two terms MOdulate and DEModulate give the modem its name.