The Network Interface Card (NIC)
The Network Interface Card (NIC) is used to link a computer to the network cable system. They provide the physical connection between the computer's expansion bus and the network cabling. The NIC boosts the computer's digital signals that transmit data so that they can be transmitted across a network cable. The NIC must also change the form of data from a wide parallel stream of 8 bits, 16 bits, or 32 bits, depending on the expansion bus, to a narrow serial stream of 1 bit in and out of the network port Thus, the NIC takes data from the computer, packages it for transmission, and acts as a gatekeeper to control access to the shared network cable. Because the NIC functions as an interface between the computer and the network cabling, it must control the flow of data to and from RAM inside the computer as well as the flow of data in and out of the network cable system. In addition, the NIC must buffer the data between the computer and cable because the computer is typically much faster than the network. This means it must temporarily store the data coming from the computer until it can place it on the network.
The NIC is installed in the same as any other expansion card. Its setup requires certain system resources, i.e., IRQ and I/O port address, as well as software. Most NICs have connectors for either thin Ethernet or twisted-pair cabling while some NICs have both connector types. The latter NICs are called combo cards. Thin Ethernet uses a round coaxial or BNC (bayonet-Neill-Concelman) connector, and UTP uses an RJ- 45 connector that similar to a telephone jack.
