What is a Network Interface Card (NIC)?

Network interface cards are also known as network adapters, LAN adapters or NIC cards for their English meaning: Network Interface Card. A network adapter is the most important device in networking.

The network card is physically connected to the network cable, which in turn is responsible for receiving and transmitting data on the physical level.

A NIC card transmits data to the network and receives data from it. It works at the data link protocol level. A network card provides a junction point for a specific type of cables, such as coaxial cable, twisted pair cable, or fiber optic cable. Interface cards for wireless networks typically have an antenna for communication with a base station. Each network interface card has a unique IP address.

Modern hardware for a network adapter can be found in different ways. In addition to the traditional PCI Ethernet card, some network adapters are PCMCIA devices or USB devices. In most laptops, network adapters are built into the circuit chip on the motherboard.

There are four techniques that are used to transfer data from a network card:

Polling is where the CPU examines the status of peripherals under program control.

Programmed I / O is where the microprocessor alerts the peripheral designated by the application of its address to the system's bus address.

I / O interruptions are where the peripheral alerts of the microprocessor that is ready to transfer data.

DMA or direct memory access is when the controller takes over the bus system and transfers the data on the network card to a memory location, thereby reducing the CPU load.