Chapter 6.3

Modem

A modem, is a device that connects a computer to a standard analog telephone line, the kind to which your telephone is connected.

Modem Overview

A device that translates data from your PC into a form that can be sent to other computers over regular phone lines. The modem also receives signals from other computers and converts it into something your computer can understand. A modem is the device most home computers use to connect to the Internet. A Modem converts digital information into sound so that it may be transmitted over telephone lines. When the modem hears this sound on the other end it converts the sound back into digital information.

You might have noticed that modem speed has been stuck at a maximum of 56 Kbps for several years. That is because the amount of data that can be transmitted across an analog telephone line might have reached a physical limit. Consequently, although there have been improvements in accuracy of data transfer and the capability of connecting and holding onto a telephone line, modems haven't gotten any faster than 56K. Because of this limit, Internet service has moved away from dial-up and toward different broadband technologies.

As a result, modems are now not usually built into newer motherboards. There are a few motherboards out there with modem risers. These are slots that take proprietary modem cards. If one of these modems fails, it is cheapest and easiest to remove it and install a standard modem in a PCI or ISA slot, if possible.

Types of Modems

There are two types of modems:

1. INTERNAL

2. EXTERNAL

Internal modems are PCI or ISA expansion cards. They tend to be simple to install; just follow the manufacturer's directions if available. They receive their power from the slot. External modems are less common today, but are still around because internal modems are often optional these days.

External modems traditionally plug into a serial port on the computer, although there are USB modems available today as well. The advantages to external modems are that you don't have to be a technician to install one and they can easily be moved from computer to computer. The disadvantages to serial-port external modems are that they require external power and are more expensive. Most or all USB modems are powered by the USB ports and aren't as expensive as serial port modems.

Above figure shows a PCI modem, a USB modem, and an external serial port modem.