Chapter 04 – Computer Networks
Network devices Modems Modem means modulator demodulator and is a device which converts a computers digital signal (i.e. modulates it) into an anologue signal for transmission over an existing telephone line. It also does the reverse process, in that it converts signals from the telephone line into digital signals (demodulates) to enable the computer to process the data. Modems are used to allow computers to connect to networks (e.g. the internet) over long distances using existing telephone networks. We used to use dial up modems which operated at about 60 kilobits (half a megabit) per second; nowadays broadband modems allow us to make use of digital networks and can give speeds of over 100 megabits per second. Advantages of current modems compared to dial up:
Network Interface Card (NIC) Every computer attached to a network needs a NIC. This enables the computer to link to the cable or wireless network.
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