A modem, or modulator-demodulator, is a device that provides the computer with connectivity to a telephone line. The modem converts (modulates) the data from a digital signal to an analog signal that is compatible with a standard phone line. The modem at the receiving end demodulates the signal, which converts it back to digital. Modems may be installed internally or attached externally to the computer using a serial or USB interface.

The installation of a NIC, which provides the interface for a host to the network, is required for each device on the network. NICs are available in different types depending on the individual device configuration. Notebook computers may have a built-in interface or use a PCMCIA card. Figure shows PCMCIA wired and wireless NICs. Desktop systems may use an internal or external NIC.

Situations that require NIC installation include the following:

• Adding a NIC to a PC that does not already have one
• Replacing a bad or damaged NIC
• Upgrading from a 10-Mbps NIC to a 10/100-Mbps NIC

To perform the installation of a NIC or modem the following resources may be required:

• Knowledge of how the adapter is configured, including jumpers and plug-and-play software
• Availability of diagnostic tools
• Ability to resolve hardware resource conflicts

Web Links Installing a Network Interface Card http://www.linfield.edu/~darnett/helpages/ NICinstall/NICStart.html