A network adapter card links a PC with the network cabling system. The network adapter card fits into one of the expansion slots of the Pc. 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 OSl model or, more specifically, the Media Access Control (MAC) sub layer of the Data Link layer. A network adapter card driver is sometimes called a MAC driver. The network adapter card's built-in ROM (read only memory) performs the functions of the Logical Link Control sub layer of the OSI Data Link layer.

Name: Principalof.jpg Views: 624 Size: 57.0 KB

The network adapter card and its accompanying software and firmware perform several roles. Microsoft identifies the following roles for the network adapter card:

• Preparing data for the transmission medium

• Sending data

• Controlling the flow of data

Preparing Data for the Transmission Medium:

The data travels on the network in serial form (one bit at a time). Inside the PC, however, data moves along the data bus (The data bus is a pathway inside your computer that carries data between the hardware components) in parallel form (8, 16, or 32 bits at a time). The network adapter card, therefore, must convert the parallel data from the bus into the serial form required for network transmission.

Sending Data:

The network adapter card places data on the network and receives data from the network. These tasks require a certain amount of data flow control. The network adapter card receives packets from the network, checks the destination address of all packets and then interrupts the CPU only if the packet is addressed to the local system.

Controlling the Flow of Data:

For two computers to exchange data, the computers' network adapter cards must be in agreement on certain transmission parameters. A newer card with a higher maximum transmission rate, for instance, might have the capability to use a data with lower transmission rate in order to communicate with a slower card. Before sending data, the cards exchange messages and agree upon such parameters as a transmission speed and a time interval between packets.