1 - Introduction
A network card also known as network adaptor, or network interface card, or NIC is a circuit board that allows
computers to communicate over the computer network. This board when connected to a cable or other wireless transfer
medium can share resources and data over the network. Network adapters function as an interface between the computer
and the network’s transfer medium. They perform two functions: inside the computer a network interface card moves
data to and from the random access memory (RAM); outside the computer, it controls the flow of data in and out of the
transmission medium (cable or wireless medium). The network card also has the ability to buffer the data transferred
over the network, because the computer is typically much faster than the speed of data being transferred over the
network.
Most NICs are internal, with the card fitting into an expansion slot inside the computer. Some computers, such as Mac Classics, use external boxes which are attached to a serial port or a SCSI port. The choice of network card primarily depends on the type of network connection you have (wired or wireless). |
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2 - Slot Type
There are different types of buses in a computer. Since the card is fitted into the slot on the motherboard, the card has to be compatible with the adaptor slot on the motherboard. Some of the standard bus types are:
2.1 - ISA
The Industry Standard Architecture (ISA) bus was used in the IBM PC. Data was transferred using eight-bit paths, which
worked well in the 8086 and 8088 CPUs, which could only handle eight bits at once. It had a speed of 8 Mbps. The release
of 80286 created a need for 16-bit cards. Printers, modems and sound cards are all examples of equipment that still tend
to use an ISA bus. Quite a few workstations still use ISA bus NICs; but this architecture offers less speed.
2.2 - PCI
Peripheral Component Interface can transfer 32 bits at a time. PCI was originally developed to help speed up graphics on
newer computers. Most new PCI cards support the new plug and play standard which allows automatic configuration of the
card. PCI slots are not backward compatible.
2.3 - PCMCIA
Personal Computer Memory Card International Association is mainly meant for laptops and notebooks. The PCMCIA v1.0 was a
standard that defined specifications for memory cards. PCMCIA v2.0 was established to allow use of other devices such as
modems, disk drives and network cards.
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3 - Cards for Wired Networks
When you're choosing a card for a wired network you will want to consider the type of cable connector you will need as well
as the speed of the network.
3.1 - Cable Types
There are two types of standard cable connectors for wired networks:
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BNC Connector: The BNC connector is cylindrical in shape, with two small prongs on the outside which allows a connector to attach to it. It has small hole for a copper wire to go into. Coaxial cables are connected to the network adaptor using the T-Connector. |
RJ-45 Connector: The RJ-45 connector looks like a normal telephone cable connector, but is larger than the telephone connector. Unlike the RJ-11 connector used in telephones which has two pairs of wires, RJ-45 uses twisted-pair cabling with four pairs of wires.
UTP (unshielded twisted-pair): or STP type (shielded twisted-pair) wires are used for organizing 10BaseT/100BaseTX networks. RJ45 connectors are used in such networks. Coaxial cables are used in 10Base2 networks, these are connected to the network adapter using BNC connectors.
3.2 - Network Speed
Your network can work at various speeds depending on the kind of Ethernet standard you choose. Let us look at the
common Ethernet standards:
Ethernet: Ethernet is the first and least expensive high-speed LAN technology. The Ethernet adapters transmit and receive data at speeds of 10 Mbps
Fast Ethernet: Fast Ethernet adapters run a network at speeds of 100 Mbps. This LAN technology costs more than Ethernet.
Gigabit Ethernet: Gigabit Ethernet systems operate at a speed of 1000 Mbps. There are two-Gigabit Ethernet standards: the 802.3z standard describes the specifications for the 1000BAse-X Gigabit Ethernet system for networks based on fiber optic; the 802.3ab standard describes the specifications for the 1000Base-T Gigabit Ethernet system for twisted pair networks. These super fast connections are often used to create large networks, as they prevent data bottlenecks, or gridlock.
For a long time, 10Base-T Ethernet, capable of passing 10 megabits of data per second, was the fastest and most popular Ethernet standard. As people used Ethernet for larger and more complex networks, and as file sizes grew, 100Base-T Ethernet (Fast Ethernet), with ten times the data transfer speed, became the Ethernet of choice.
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4 - Cards for Wireless Networks
A Wireless network does not require cables and offers unique features for mobile users. The earlier wireless networks allowed data transfer at rates of 2 Mbps. Today wireless networks offer data transfer speed of up to 11Mbit/s speed around 100m indoors and up to 300m outdoors. The crucial attribute to consider when purchasing a network card for a wireless network is compatibility with wireless network standard. Cost is also a factor to consider when opting for wireless network cards as wireless devices are more expensive than devices for wired networks.
Compatibility with wireless network standard
The network adapter should be compatible with your chosen network standard. The various wireless network standards are:
802.11a wireless networking: 802.11a uses the 5GHz band to transmit data at up to 54 Mbps. It experiences much lesser interference than 802.11b and 802.11g, and handles larger files. The cost of setting up a network with this standard is high.
| 802.11b wireless networking: 802.11b uses 2.4 GHz band to transfer data and hence 802.11b can experience interference from cordless phones and similar devices using the same spectrum. 802.11b offers theoretical transmission speeds up to 11 Mbps. |
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802.11g wireless networking: Using the 2.4 GHz band, 802.11g can experience interference from cordless phones and similar devices using the same spectrum. It offers data transfer speeds up to and exceeding 20 Mbps and is backward-compatible with 802.11b. 802.11g offers higher throughput than 802.11b.
A network card plays a key role in deciding the speed of communication over the network; hence it is important that one gathers all possible information about network cards before taking the final purchase decision.
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