The dubious Network Interface Card (NIC) is an adapter that allows you to connect your PC to a Local Area Network (LAN) through an Ethernet interface. These adapters are available in ISA, EISA, PCI, and CNR format. Pictured here are PCI adapters.
NICs support a wide variety of physical interface protocols. Pictured above are 10 BASE T/100 BASE TX adapters. The 10/100 refers to the speed of the interface, either 10Mbps or 100Mbps. Some NICs are only 10 BASE T or 10Mbps only. The BASE T or TX refers to the physical interface protocol, namely 8 conductor Unshielded Twisted Pair (UTP) cabling. It is possible to find Shielded TP (STP) cabling. There are several manufacturers of NICs, the ones I like the best are 3COM and Intel 10/100s.
The above NIC shows the three most prevalent types of physical interfaces used, namely 10BASE2/10BASE5/10BASE-T via BNC/AUI/RJ-45 connectors. The BNC connector is for networks that use coaxial cable. The AUI connector is a special purpose 15 pin DIN for connection to special HUBs, Routers, etc.
Most NICs have Light Emitting Diodes (LEDs) that indicate the status of the card. Typically there will be one LED for Line Connect status which lights green if the card senses a good connection to another device such as a HUB. This tells you the card sees the physical interface (cable connection). Another LED typically found is a data LED that flashes green when data is being passed, which indicates the network is operating and being accessed. A third LED sometimes found is the speed LED, it will light if the network is running at 100Mbps.
The most important factor in getting a NIC to function is the drivers. If you are having problems with your NIC, download the drivers from the manufacturer and install them. I have seen a lot of "no name" NICs that do not function because the drivers don't work or were lost and can't be found. I highly recommend buying a name brand NIC so you can get on another PC to download the drivers. Think about it, if you don't know who manufactured your NIC, how can you find the drivers?
Wireless NICs and 1000Base-TX NICs that use either copper or fiber optic cable are also available.
