Friday, June 24, 2011

Network Adapter

Network Adapter

A computer communicates on the network through a network interface card or network adapter.

Network adapter plugs into the motherboard of a computer and into a network cable. Network adapters perform all the functions required to communicate on a network. They convert data from the form stored in the computer to the form transmitted or received on the cable.

Network Adapter

Network adapter

A network adapter receives data to be transmitted from the motherboard of a computer into an area of memory called a buffer. The data in the buffer is then passed through some electronics that calculates a checksum value for the block of data and adds address information, which indicates the address of the destination card and its own address, which indicates where the data is from. Each network adapter card is assigned a permanent unique address at the time of manufacture. The block is now referred to as a frame. The network adapter then transmits the frame one bit at a time onto the network cable. The address information is sent first, followed by the data and then the checksum.

A network adapter card must match both the bus of the computer it is placed in, the type of network to which it is connected and the media type to which it is attached.

The bus could be one of ISA, EISA, Micro Channel, VESA Local Bus, PCI, NuBus, PC Card (PCMCIA) or a proprietary local bus. Some computers have more than one bus, e.g. both an ISA and a PCI bus.

The network could be Ethernet, Fast Ethernet, Token Ring, ARCnet, ATM, or a proprietary network standard.

The media type could be coaxial cable, unshielded twisted pair, optical fibre, radio or wireless Infra Red.