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Defining a Network Adapter Card
A network adapter card links a PC with the network cabling system (see Figure 10.1). The network adapter card fits into one of the PC’s expansion slots. The card has one or more user-accessible ports to which the network cabling medium is connected.

Like other hardware devices, a network adapter card has a driver, a software component that manages the device. The network adapter card driver serves a crucial role in the networking architecture. Adapter card drivers inhabit the Data Link layer of the OSI model (see Chapter 2, “Networking Standards,” for more information), or, more specifically, the Media Access Control (MAC) sublayer of the Data Link layer. A network adapter card driver sometimes is also called a MAC driver. As Chapter 2 mentions, the NDIS and ODI standards provide a uniform interface for the adapter card driver, enabling one adapter to support multiple protocols and making one protocol accessible to multiple adapters.

The network adapter card’s built-in ROM (read only memory) performs the functions of the Logical Link Control sublayer of the OSI Data Link layer.

The network adapter card and its accompanying software and firmware perform several roles. Microsoft identifies the following roles for the network adapter card:
Of course, the network adapter must also play these roles in reverse, receiving data from the network and converting that data to the form necessary for the local system.

Further Information