What Makes a NIC Tick?

A typical NIC is an add-in card that's configured to work inside your PC. Its role is to work both sides of the network connection, like this:

• The NIC plugs into your computer's bus (or a special adapter slot) so that it can talk to the CPU (or CPUs) and the CPU can talk to it. This essentially defines a NIC's most important role namely, it permits a computer to access the network medium and vice versa.

• A NIC's accommodation for a network connection (where the medium plugs in) requires an external connector to connect the network medium to the NIC in some form or fashion. Some NICs include more than one connector, so if you change your network (or your mind), you don't have to throw out the old NIC and put in a new one.

• Your network technology determines the details of how a NIC accesses the network medium. There are NICs for Ethernet, token ring, Fiber Distributed Data Interface (FDDI), and so on. NICs don't normally support more than one network technology.

Figure 6-1 shows all the important connections on a NIC, including the bus connector (which makes the NIC and the CPU accessible to one another) and the media interface (which makes the NIC and the networking medium accessible to each other). Media connectors vary with the networking technology and physical media in use. By learning to recognize what you have, you can select the NIC or NICs that are right for your network.

Figure 6-1: The NIC creates a bridge between your computer and the network.

Figure 6-1 shows a so-called three-way combo card for Ethernet, with an RJ-45 connector for twisted pair (10BaseT), a BNC connector for ThinWire (10Base2), and an AUI connector for ThickWire (10Base5). If this sounds like sheer gibberish, don't worry you can explore exactly what all this gobbledygook means in Chapter 7.

Not all NICs take the form of adapter cards that plug into a bus inside your computer. Some laptops, portables, and other machines can't accommodate standard internal interfaces like conventional desktop PCs can. Especially on laptops, you must often install PC card adapters (formerly known as PCMCIA, or Personal Computer Memory Card International Association, adapters) according to your networking whims.

PC cards look a lot like fat credit cards and are about the same size . You slide them into and out of your computer's PC card slot. Laptops sometimes require a NIC PC card for a network connection in the office and a modem for remote access to network resources when the laptop owner is away from the office.