What is a Network Card

Netword CrtdNetwork Card also known as Network Interface Card or NIC, network adapter, LAN Adapter, is a printed circuit board containing the necessary hardware used to connect a computer to a network or other computer. It provide a dedicated, full-time connection to a network.
In Seven Layer of OSI Model, Network Card falls both to Physical layer and Data Link layer device. 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. It implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard.

Ethernet is the most common network technology that exist. It has achieved near-ubiquity since the mid-1990s. Every Ethernet network card has a unique 48-bit serial number called a MAC address, which is stored in ROM carried on the card. Every computer on an Ethernet network must have a card with a unique MAC address. No two cards ever manufactured share the same address. This is accomplished by the Institute of Electrical and Electronics Engineers (IEEE), which is responsible for assigning unique MAC addresses to the vendors of network interface controllers.

There are four techniques used to transfer data, the network card may use one or more of these techniques.
  • Polling is where the microprocessor 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's ready to transfer data.
  • DMA is where the 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.
A network card typically has a twisted pair, BNC, or AUI socket where the network cable is connected, and a few LEDs to inform the user of whether the network is active, and whether or not there is data being transmitted on it. The Network Cards are typically available in 10/100/1000 Mbit/s(Mbit/s). This means they can support a transfer rate of 10 or 100 or 1000 Megabits per second.
Most computers nowadays comes with a built-in network card on their motherboard.