Have you ever taken a look at all the port and connectors available at the back of your computer tower? You will find connectors like for LAN, Sound, Parallel Port (15 Pin), Serial Port (9 Pin), Serial Port (15 Pin), VGA (15 Pin) and many more. We know that VGA is used for connecting the display device, parallel port is used for connecting printers, serial ports are used for connecting old external dial-up modems, but is there any other use of serial ports? Yes the 9 pin serial port can be used for connecting two computers together so that they can communicate with each other and share data and resources together. The device which is required for making the connection over these serial ports is called a null modem and it is nothing but a simple cable with 9 pin serial port connectors at both its ends. The RS 232 serial port is quite an old component of motherboards and you will seldom find it in motherboards available today. But if you have this port available in your laptop or computer then you can easily use it to connect the two devices together.
Step 1: If you do not have an RS 232 Serial port available in your device still you can make it work over the USB port by getting USB to RS232 convertor. This will allow you to connect you null modem over USB.
Step 2: While connecting the null modem to a laptop not much of precaution is required but if you are connecting it to your desktop computer then better would be if you switch off the computer. This is precaution to avoid any electrical shock. Computer towers are generally metallic and ten to accumulate static charge while they are ON. If the tower is not properly grounded then you may get electric shock on touching it by your naked hands. So please turn off the computer, unplug it from the power supply and only then connect the null modem to the RS 232 serial port at the back of the tower.
Step 3: Now please check the orientation of the pins on the connector. This will reduce the chances of you trying to connect it to the MIDI port which is also a 9 pin connector of same shape.
Step 4: Once you have made the connection insert the disk which you would have received with the null modem cable. This disk carries special software which makes the communication between the two computers possible over the serial port. Windows by default has no way to control null modem and you would need this software installed on both the machines. In case you do not have the disk then search for software called Laplink which is meant for solving the same purpose.