What is a Network Interface Card or NIC Adapter?
NIC stands for Network Interface Card. NIC are also known as network interface cards, network adapter or LAN adapter. A NIC adapter is the most important device in building network. The network adapter card is physically attached to the network cabling. It is responsible for receiving and transmitting data at the physical level.
A NIC adapter transmits data onto the network and receives data from the network. It works at the data link protocol level. A NIC provides an attachment point for a specific type of cable, such as coaxial cable, twisted-pair cable, or fiber-optic cable. NICs for wireless LANs typically have an antenna for communication with a base station. A network adapter has a unique IP address.
Modern network adapter hardware exists in several forms. Besides traditional PCI Ethernet cards, some network adapters are PCMCIA devices or USB devices. Some wireless network adapter gear for laptop computers are integrated circuit chips pre-installed inside the computer.
There are four techniques used for transfer of data a NIC may use one or more of these techniques.
- Polling is where the CPU examines the status of the peripheral under program control.
- Programmed I/O is where the microprocessor alerts the designated peripheral by applying its address to the system’s address bus.
- Interrupt-driven I/O is where the peripheral alerts the microprocessor that it is ready to transfer data.
- DMA or Direct Memory Access is when a controller takes charge of the system bus and transfers data from the NIC to a memory location, thus reducing CPU load.