A network interface controller (also known as a network interface card, network adapter, LAN adapter and by similar terms) is a computer hardware component that connects a computer to a computer network.

NICs can be either built into the main board or an expansion card.

The Ethernet capabilities are either integrated into the motherboard chipset or implemented via a low-cost dedicated Ethernet chip, connected through the PCI (or the newer PCI express) bus.

The network controller implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet, Wi-Fi etc.

Every Ethernet network controller has a unique 48-bit serial number called a MAC address, which is stored in read-only memory.

The NIC allows computers to communicate over a computer network. It is both an OSI layer 1 (physical layer) and layer 2 (data link layer) device, as it provides physical access to a networking medium and provides a low-level addressing system through the use of MAC addresses. It allows users to connect to each other either by using cables or wirelessly.

The NIC may use one or more of four techniques to transfer data:

* 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.[dubious – discuss]

* Interrupt-driven I/O is where the peripheral alerts the microprocessor that it is ready to transfer data.

* Direct memory access is where an intelligent peripheral assumes control of the system bus to access memory directly. This removes load from the CPU but requires a separate processor on the card.

An Ethernet network controller typically has an 8P8C socket where the network cable is connected. Older NICs also supplied BNC, or AUI connections. A few LEDs inform the user of whether the network is active, and whether or not data transmission occurs. Ethernet network controllers typically support 10 Mbit/s Ethernet, 100 Mbit/s Ethernet, and 1000 Mbit/s Ethernet varieties. Such controllers are designated 10/100/1000 – this means they can support a notional maximum transfer rate of 10, 100 or 1000 Megabits per second.


Network via:

* Fast Ethernet
* Gigabit Ethernet
* Optical fiber
* Token ring

Connects to Motherboard via:

* Integrated
* PCI Connector
* ISA Connector
* FireWire

10 Mbit/s
100 Mbit/s
1000 Mbit/s
up to 160 Gbit/s

Common manufacturers

Related External Links

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