System resources A NIC is configured to the computer with an IRQ, an I/O
address, and a DMA channel. A NIC commonly uses IRQ3, IRQ5, or IRQ10 and
an I/O address of 300h.
Transceiver type Some NICs are capable of attaching to more than one media
type, such as UTP and coaxial. Each different cable medium requires a different
type of transceiver, the device that transmits and receives data from the network.
Data bus compatibility NICs are designed with compatibility to a particular
data bus architecture. Most newer NICs are PCI (Peripheral Component
Interconnect), but there are still many ISA (Industry Standard Architecture)
legacy NICs still in use.
NIC Connectors
Often the media type in use on the network controls other hardware decisions, such as the
NIC itself and the type and style of connectors linking it to the network media. Table 20-3
lists the connectors used by each of the popular media types.
Network Topologies
A network’s topology defines two things. The first is the network’s general shape and ar-
rangement. The second is the technologies used to support the network. The most com-
mon topology in use is the bus (which is generally referred to as Ethernet, the most
commontypeofbusnetwork)andring(mostcommonlycalledTokenRing,aftertheIBM
implementation that is commonly used) topologies.
Here is a brief description of each of the most common network topologies:
Bus/Ethernet Nodes are connected to hubs or switches, which are in turn
connected to a central backbone cable that runs the length of the network. The
bus topology is commonly used for Ethernet networks. Refer back to Figure 20-8
for an illustration of how the bus topology is typically implemented.
(^524) PC Hardware: A Beginner’s Guide
Media Connectors Used
Thinnet BNC (Bayonet Neil-Concelman) connectors
Thicknet AUI (Attachment Unit Interface) connectors
UTP RJ-45
Fiber optic ST connectors
Table 20-3. Cable Media and Associated Connectors