Network Interface Cards

The network interface card (NIC), or network card, is a device installed on the system that is responsible for sending and receiving data onto the network. The network card is responsible for preparing data from the system to be transported on the wire by converting the outbound data from a parallel format (due to bus width of the bus architecture that the card is sitting in) to electrical signals that will travel along the network media. On the receiving end, the network card is responsible for receiving the electrical signal and converting it to data that is understood by the system.

The network card also is known as a network adapter; it can be installed in the system after the system has been purchased, or the system comes with a network card built in. A system that comes with a network card built in is said to have an integrated network card—meaning the card is integrated into the system. Figure 3-1
shows an integrated network card port on the side of a laptop; desktop computers typically have the port on the back of the computer.


 Network cards that are installed on the computer as an add-on can be installed into the system by inserting the card into the expansion bus of the system (usually PCI, but in the past it was ISA) or by plugging
in a USB device. There are a number of different types of expansion slots in the system. When installing a network card, you will need to make sure that you get the correct type of card for the particular type of expansion slot. For example, a PCI card is placed in a PCI slot and will not fit into an ISA or AGP slot. The
following is a list of popular expansion bus architectures, and Figure 3-2 shows a picture of an ISA network interface card.

- ISA Industry Standard Architecture (ISA) is an old bus architecture that runs at 8 MHz and supports 8- or 16-bit cards.
-MCA Microchannel Architecture (MCA) was built by IBM and has a 32-bit architecture that runs at 10 MHz.
-VESA Video Electronics Standards Association (VESA, also known as VESA local bus, or VLB) at the time ran at the system speed (which was around 33 MHz); it has a 32-bit architecture.
-EISA Extended Industry Standard Architecture (EISA) is the upgrade to ISA that supports 32-bit cards running at 8 MHz.
-PCI Peripheral Component Interconnect (PCI) is the popular bus architecture today for adding cards to the system. PCI runs at 33 MHz and has a 32-bit or 64-bit bus architecture. Most network cards today are PCI.
-AGP Advanced Graphics Port (AGP) is the new graphics standard that runs at 66 MHz and is used by video cards.
-PCMCIA Personal Computer Memory Card Industry Association (PCMCIA) is the bus architecture used in laptop computers. PCMCIA has a 16-bit architecture that runs at 33 MHz.