What Is Null-modem?

Null Modem is used for communication between two computers or printers using cable  name as RS-232 Serial cable. RS-232 is standard serial binary data signal connection.
Method that is used for transmitting and receiving data is cross linked cable used. Normally Null Modems are used for file transfer between computers or remote Data Equipment. By using Null Modem both pieces of software allow the mapping of a hard disk on one computer as a network drive on the other computer By using this No ethernet card (such as a network interface card or a modem) is required.

It is also used for gaming purpose. by using  null modem cables a "head-to-head" gaming between two players at different computers in the same room can be played. (The length of a null modem cable is limited to 30 feet)it is still used for communication between computers. Especially for portable computers.

Null modem connects computer, terminal and printer etc by using RS-232 serial cable. We can say that Null modem is a communication method. While null modem receive lines are cross linked and some time handshake lines are also cross linked, it depends upon the purpose.

Null modems are generally used for remote operation or transfer of files between computers. Microsoft windows operating system and MS-DOS both software allow the mapping of hard disk. For this mapping of hard disk, no Ethernet card such as a network interface card is required. But the popularity of Ethernet makes the use of Null modem less common. Ethernet hardware is more efficient and faster then null modem.

Another null modem is also available which is called a virtual null modem .It is also a communication technique. It uses virtual serial port and link two computer applications directly. But unlike null modem, virtual modem is software solution and it equates hardware null modem in the computer. All the qualities of null modem is available in virtual null modem but there are some other advantages also. Virtual null modem has more transmission speed of serial data as campire to null modem. Also unlimited number of virtual connections is also possible through virtual null modem.