Find the role of hardware connection devices, network cards and communication cables in computer net

Computer networks mainly include network terminals (PCs, workstations, computing centers, printing file servers, data storage servers, etc.), network adapters (network cards), modems (cats), communication lines (cables, optical cables, wireless transmitting and receiving equipment, etc.).

The network terminal completes various practical applications; The communication line transmits various photoelectric signals and connects the terminals; Because the modern digital electronic computer processes the digital signal, and the digital signal direct transmission attenuation is fast, easy to interfere, and there is a distance limitation, so the network connection needs the modem (cat) to complete the two-way conversion between the digital signal processed by the computer and the analog signal transmitted in the communication line; The network adapter (network card) is responsible for transmission control, data buffering, and signal matching of the received data sent to the network.

A personal computer is a small network, a variety of input devices (keyboard, mouse, handwriting, microphone, scanner, camera, digital camera, etc.), output devices (monitor, audio, printer, projector, etc.), data computing unit (** processor - CPU), storage devices (memory, hard disk, optical drive, U disk, memory card, etc.) through the computer motherboard and various adapters (graphics card, sound card, etc., including network card, some have been integrated on the motherboard) connected together. A network, on the other hand, can be seen as separating and amplifying the various functional components of a computer. With the continuous development of computer technology, computers have an increasingly profound impact on human production and life because of the development of networks.

Smartphones (handheld computers), smart home appliances, cloud home appliances, etc. are the extension of personal computers (PCs) to more practical applications, network computing, network printing, network storage (network disk) and a new generation of faster communication transmission technology, so that people gradually get rid of the shackles of desktops. Networks are everywhere, and networks are computers.

Network card: also known as a network adapter, it is used to connect to the network, it is just a device that sends and receives signals.

Communication cable: The communication between the network card and the LAN is carried out in serial transmission mode by cable or twisted pair.

A coaxial cable consists of a hollow outer cylindrical conductor (copper mesh) and an inner conductor (cable copper core) located on the central axis, and the inner conductor is separated from the cylindrical conductor and between the cylindrical conductor and the outside world by an insulating material, as shown in Figure 2-10. It is characterized by good anti-interference ability, stable transmission data, and cheap, and is widely used with sleepy comics, such as closed-circuit television lines.

Nowadays, thin cable networking is generally used in computer LANs. Thin cables are used for bus-type network cabling connections like a hidden skin. Use the T-type BNC interface connector to connect the BNC interface network card, and install 50 termination resistors at both ends of the coaxial cable.

Each trunk section of the network is up to 185 meters long, and each trunk can access up to 30 users. If you want to widen the network range, you need to use repeaters, such as using 4 repeaters to connect 5 network segments, so that the maximum distance of the network reaches 925 meters. The thin cable is easy to install, and the cost is low, but due to the limitation of the network wiring structure, its daily maintenance is not very convenient, once a user fails, it will affect the normal work of other users.

The thick cable is suitable for the network trunk of the large area network with a difference in the size of the stove, with a longer wiring distance and better reliability. Users typically use an external transceiver to connect to the network trunk. The length of each segment in the thick cable LAN can be up to 500 meters, and the maximum length of each segment can be up to 2,500 meters when five segments are connected by four repeaters.

If the network is directly connected to the NIC with a thick cable, the NIC must have an AUI interface (15-pin D-type interface). Although the LAN formed by thick cable has high performance and large transmission distance, it is difficult to install and maintain the network, and the cost is high.