A crossover cable might sound like a thing of the past, but it is still in use today in various capacities. A crossover cable is used to interconnect two computers for the purpose of direct communication. Another name for crossover cable is null modem.

You might want to test the behavior of one computer by connecting it to another. You might want to connect two computers to avoid having to buy a hub. You and a friend might want to compete against each other in a multiplayer game. In each of these instances, you can use a crossover cable to achieve your goals.

For the first two instances, you will want to make sure that the two computers are in the same Workgroup. If they are not, then they will not be able to “see” each other. Once they are members of the same Workgroup, the data transfer or monitoring can begin. Actually, the Workgroup requirement might be in force for multiplayer gaming as well. Check the protocols for both the game and the crossover cable to be sure.

Many network cards have the functions inherent to a crossover cable built in. In this case, you need no crossover cable as long as both computers are connected to the same network, primarily using the same modem or router. The network card does the work that would normally be done by the crossover cable.

You can buy a crossover cable at most computer stores and online computer equipment vendors. You can also make your own from commonly available materials; several do-it-yourself websites can show you how. If making your own, remember that in a crossover cable, the signal pins that receive on one end are connected to the pins that transmit on the other. This is different from straight-through cable, in which the pins are connected like to like.

A crossover cable can also be used to connect two Ethernet devices. These Ethernet devices can be single computers, or they can be networks. The principle is the same, but the connection speed and scheme are different, as is the purpose of the connection. In all cases, however, the functionality of the crossover cable is that the data send and receive functions are crossed over at both ends of the cable, enabling full data transfer between computers, routers, and even networks.