To connect a computer to the network, the device that should be installed is a "modem" or "network card". Network cards are used to connect computers and communication cables for high-speed data transmission between computers via cables; while modems are necessary equipment for PCs to access the Internet through telephone lines (dial-up mode). Accessing the Internet (Internet) through dial-up (telephone network) means that the user's computer uses a modem to connect to the ISP through the telephone network, and then accesses the Internet through the ISP connection.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
Usually when a computer wants to access the Internet, the device that should be installed ismodemornetwork card.
Network card
A network card is a piece of computer hardware designed to allow computers to communicate on a computer network. Since it has a MAC address, it falls between Layer 1 and Layer 2 of the OSI model. It allows users to connect to each other via cable or wirelessly.
Network cards are used to connect computers and communication cables to facilitate high-speed data transmission between computers via cables.
The communication between the network card and the LAN is carried out through serial transmission through cables or twisted pairs. The communication between the network card and the computer is carried out in parallel transmission through the I/O bus on the computer motherboard. Therefore, an important function of the network card is to perform serial/parallel conversion. Since the data rate on the network is not the same as the data rate on the computer bus, a memory chip that caches the data must be installed in the network card.
Modem
Modem is the abbreviation of modulator and demodulator. It is a kind of computer hardware that can translate the digital signal of the computer. into analog signals that can be transmitted along ordinary telephone lines, and these analog signals can be received by another modem at the other end of the line and translated into a language that the computer can understand. This simple process completes communication between two computers.
A modem is an essential device for a PC to access the Internet through a telephone line (dial-up method).
Accessing the Internet (Internet) through dial-up (telephone network) means that the user's computer uses a modem to connect to the ISP through the telephone network, and then accesses the Internet through the ISP connection.
The user's computer and the ISP's remote access server (RAS, remote access server) are connected to the telephone network through a modem. When the user accesses the Internet, he dials The ISP's RAS establishes a connection and accesses the Internet through the ISP's router.
The telephone network is designed to transmit analog signals. Digital signals from computers cannot be transmitted directly over ordinary telephone lines, so a practical modem is required. At the sending end, the modem converts the digital signals in the computer into analog signals that can be transmitted over the telephone line; at the receiving end, the modem converts the received analog signals into digital signals that can be recognized by the computer.
How dial-up Internet access works
The number of telephone trunks that an ISP can provide is related to the success rate of establishing a connection with the ISP. Each telephone trunk can only support one user's access at a time. The fewer telephone trunks provided by the ISP, the lower the success rate for users to establish a connection with the ISP's RAS. On the user side, a computer can be directly connected to the telephone network through a modem, or a proxy server can be used to indirectly connect a local area network to the telephone network through a modem.
The maximum transmission rate of better lines can reach 56Kbps, general lines can only reach 33.6Kbps, and the transmission rate of poor lines will be lower. Since phone lines support limited transmission rates, this method is suitable for personal or small business use.
Due to technical reasons, the reliability of dial-up lines is not high enough. During the transmission of large amounts of information, the connection is sometimes interrupted, so this method is not suitable for providing Internet services.
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