NIC (Network Interface Card):
A Network Interface Card (NIC) is a network card or we can say
add-on-card configured to fit our computer. The work (role) of network
card is our computer is to work on both side of the network connection.
Network Interface Card (NICs) connects the PC to the network cable.
NICs must be matched to the type of network and the type of network
cable that you are using. It is important to choose a NICs manufacturers
provide models that can connect to multiple network type, such as
Coaxial, Twisted pair, and fiber optic.
Now days the network card, which comes in 16 bit from going to be
absolute and replace by new technology cards, these card comes in the
form of 32 bit also called Gigabit Ethernet. There is lot of advantage
the immediate choice for network interface card is fast Ethernet PCI
adapter. Beside lower prices, fast Ethernet is compatible with older 10
MBPS network.
Ideally the card should support following features.
i) Support for plug play (PnP).
ii) Bus
mastering technology since it helps economize on CPU utilization by
allowing network request to by pass the processor and go straight to
adapter.
iii) Support for remote boot ROM.
The
Network Interface Card (NIC), or the adapter card, is a card that you
use to connect your workstation to the files servers or the other
workstations. You need to be aware of various components of a Network
Interface Card.
· Interrupt Request (IRQ) Settings.
· Base I/O address
· Direct Memory Access (DMA) chips.
Your
computer will depend of the type of topology you are
using-specifically, Peer-to-Peer versus Client-Server. Also, the card
will probably be cable-specific that is, it may need to use coaxial
cable, 10/100 BaseT or Fiber-optic cable, depending on the card.
IRQ:
Some memory chips are sited on your NIC. The purpose of these memory
chips is to give packets that are addressed to your machine someplace to
go when they arrive at your workstation. Unfortunately, the computer’s
CPU, which is the brains of the operation, cannot see that memory
sitting on the NIC. Therefore, somebody has to move that information
from the memory of the NIC to the main memory of your system so that the
CPU can process it. The component charged with the task of moving
information from the memory of the NIC to your main memory is also a
CPU, but his CPU is located on the network adapter.
Each device that needs to use an IRQ must use a unique IRQ. Otherwise,
you can expect your computer to crash! Using different IRQs for
different cards in your system is not optional ;it is very important.
Base Memory Address:
The location that an adapter card occupies in memory is refereed to its
base memory address or base I/O address. This is the location that the
CPU goes to when it needs to exchange information with the adapter card.
The IRQ is used to signal to the CPU that there is information waiting.
Then the CPU access these memory addresses to retrieve that
information. It can also work in reverse when the system is sending
information to the network.
DMA chips (Direct Memory Access):
The next order of business is to find out how DMA chips move the information from the NIC to main memory.
Your motherboard contains two DMA chips, and each chips supports four
DMA channels, making a total of eight DMA channels on your motherboard.
Every device that needs to use DMA must use a unique DMA channel.
