A device is an example of technology. A null modem cable is a device.
Null Device was created in 1995.
A user guide on networking with a null modem can be found in various places. One place is to check the information that came with the null modem. If one cannot find the answers they seek there, then another place is to check with a networking expert.
A null modem is a cable connecting two serial ports with the input and outputs and device control lines crossed over, so the input pin on one port is connected to the output pin on the other, and so on. It is also called a 'cross-over cable'. A null modem allows two computers to be connected together using their serial ports without using modems (hence null modem). If you used a standard ('straight') serial cable, the two inputs would be connected together, and the two outputs, and so on, so the computers would not be able to communicate. Modems have their data and control pins reversed internally, so a 'straight' cable is used between a computer and a modem.
A modem
modem
A null modem cable is a cable which connects two computers directly. The connection is made using serial interface and actually requires no modem or phone line. These connections can be useful for some legacy applications, however due to the availability of low cost networking equipment null modem connections are now rarely used.
You can find a Null Modem Serial Cable for sale from stores such as Walmart, Tiger Direct and Radio Shack. You can also get these cables from retailers such as Amazon.
The device you are referring to is called a Modem.
A modem (Modulator-demodulator) is both. It allows you to input data (download) and output data (upload).
try a null modem serial connection
A modem is a peripheral device based on the fact that peripheral devices are devices located on the outside of a computer
modem is device which is used to connect the Internet to computer