Modems – A computer installed with an Internet-enabled software can read the messages directly from the Internet without the help of any equipment. It is then said to be directly connected to the Internet. But if it does not have such a software installed, a separate modem is needed for connection to the Internet. It is because the data stored in a computer and those transmitted over a telephone line are in different forms.

Data stored in computers are in digital form whereas those transmitted on phone lines are in analog form. So, when we connect two computers over a telephone, the data coming out of the computer is in digital form which has to be transformed into analog format before transmitting over the telephone line. Similar conversion is required for acceptance by the computer. The simple modem is a flat box type that is connected to the ports outside the computer. The speed of data transmission depends upon the speed of the modem installed at the user’s computer and that on the dialing end.

 Modems are available at different speeds such as 2400bps, 9600bps, 14.4bps, 28.8kbps, and many more. The device is used for these conversions is known as Modem. The term modem comprises of the mod (taken from modulation), and em (taken from demodulation).

Types of Modems – There are two types of modem

• Internal modem
• External modem

These two types are as discussed below –

Internal Modem – An internal modem uses an adaptor card that fits into an expansion slot inside the computer. The internal modem occupies less space and is more convenient to use but it can serve a single computer only.

At present, personal computers are available with pre-installed that is an internal modem. The internal modem is a PCB (Printed Circuit Board) with a modem chip which is installed on the computer. The internal modems are cheaper than the external modems. The Internal modems get power supply from the computer itself but power disconnection is not easy.

External Modem – The external modem is a small box connected to the computer with a cable. It offers more flexibility and can be moved from one computer to another. There is a separate power point is needed for external modems.

The problem of external modems can be easily handled as these can be switched off any time because it needs more space and separate power lines.

Note – The fastest modems available are of 56.6 kbps (kilo bits per second) speed. Installation of a fast speed modem does not yield the desired results if the dial-up modem at the other end is of a lower speed.