MODEMs
A MODEM is a device that allows you to communicate with another computer. Because the MODEM can receive and send data it is considered as both an input and output device. The main purpose of a MODEM is to translate data signals between the computer and the telephone line.

  • To send data to another computer the MODEM translates the format or language a computer uses (digital) to the format or language a telephone line uses (analog).

  • To Receive data from another computer the MODEM translates the data back from the telephone line (analog) to the format the computer understands (digital).

  • MODEMS allow programs and data files to be transmitted from either within the local community or world wide.

There are two basic types of MODEMS.
  • Internal- Mounted inside the computer.

  • External- Placed on the desktop outside the computer.

Internal MODEMS - are installed inside your computer in one of the expansion slots on the motherboard. They are usually much cheaper than the external type and naturally take up less desk space. The problem is that internal MODEMs usually do not offer the speed capability that external MODEMs do.

External MODEMs - Offer the advantage of visable status lights on the front of the MODEM cabinet. These lights help keep you informed on the status your connection with the other computer. These MODEMs also offer a capability of higher speed, and allow for easier transfer of data from one computer to another.

    Communications Software - Your MODEM is controlled by using communications software. This software serves as a translator between you and the MODEM Hardware. This software handles all the technical details of communications.

    There are three basic types of communications programs.

    • General Communications - These programs allow you to access information services such as local bulletin board, Electronic Email services, and other MODEM equipped PCs. Some of the more popular programs are:

      • Procomm Plus - DOS and Windows based

      • Crosstalk - DOS based.

      • Dial-Up Networking - Windows 3.11/95/98 based.

      • Blast - DOS Based.

      • Terminal - Windows based.

    • Front-End Based - These are programs designed to provide access to information and mail services such as AOL, Prodigy, and Compuserve. The software needed to communicate with these services is usually provided by the service provider.

    • Remote Control Programs - This type program lets you control one computer from another. You can use this type program to access the computer in your office from your home computer. Once you have established a connection you will see on your screen exactly what appears on your computer in the office.

    Your MODEM is connected to the rear of your computer via a special cable. This cable is connected to one of your Communications (COM) ports.

    On most PCs, Serial ports are usually female type 9-pin or 25-pin plugs. Most PCs have either one or two serial ports installed at the back of the PC.