What does the crab brand mean?

The crab card network card is a realtek network card. The icon looks like a crab, so it is called a crab card network card.

The network card is equipped with a processor and memory (including RAM and ROM). The communication between network card and LAN is realized by serial transmission of cable or twisted pair.

The communication between the network card and the computer is carried out through parallel transmission of I/O bus on the computer motherboard. Therefore, an important function of the network card is serial/parallel conversion. Because the data rate on the network is different from that on the computer bus, a memory chip for caching data must be installed in the network card.

Network card function

1, data encapsulation and decapsulation

When sending, the data transmitted by the upper layer is added with a header and a trailer to form an Ethernet frame. When receiving, the Ethernet frame is stripped of its head and tail, and then sent to the upper layer.

2. Link management

It is mainly realized by CSMA/CD (Carrier Sense Multiple Access/Collision Detection) protocol.

3. Data encoding and decoding

Manchester coding and decoding. Manchester code, also known as digital bidirectional code and phase coding (PE), is one of the commonly used binary code line coding methods, which is used by the physical layer to encode the clock and data of synchronous bit stream. In communications, a code used to represent the combination of data and timing signals in a bit stream to be transmitted. Commonly used in Ethernet communication, train bus control, industrial bus and other fields.