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(mō´dem) (n.) Short for modulator-demodulator. A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts between these two forms. Fortunately, there is one standard interface for connecting external modems to computers called RS-232. Consequently, any external modem can be attached to any computer that has an RS-232 port, which almost all personal computers have. There are also modems that come as an expansion board that you can insert into a vacant expansion slot. These are sometimes called onboard or internal modems. While the modem interfaces are standardized, a number of different protocols for formatting data to be transmitted over telephone lines exist. Some, like CCITT V.34, are official standards, while others have been developed by private companies. Most modems have built-in support for the more common protocols -- at slow data transmission speeds at least, most modems can communicate with each other. At high transmission speeds, however, the protocols are less standardized. Aside from the transmission protocols that they support, the following characteristics distinguish one modem from another: To get the most out of a modem, you should have a communications software package, a program that simplifies the task of transferring data. See "Dial-Up Modem Standards"
and "Types
of Internet Connections" in the Quick Reference section of Webopedia.
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GlobalSpec.com: Computer Modems
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Provides database of suppliers for computer modems. Includes catalogs, technical information, and supplier contact information.
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 Serial Communication Overview 
Outlines the technology behind the PC modem, the associated CCITT standards and higher performance solutions such as ISDN, and xDSL. Includes graphics and diagram. This page is from "The PC Technology Guide."
56K.COM - 56K modem home page
Provides information and resources for the 56K owner and buyer. Offers newsflashes, a primer, upgrade and buyer's guides, modem initialization strings, drivers, and firmware updates.
U.S. Robotics home page
The is the home page for US Robotics, a leading modem manufacturer. This page offers links to company information, as well as products and services for the home, office and business user.
Modem Express
Home page of Modem Express, a data communication repair company who has purchased the rights to Hayes warranty and repair inventory. For more information regarding Hayes and Hayes products, see the news section of their site.
PC Mechanic's Modem Page
Step-by-step instructions on how to install internal and external modems.
Troubleshooting Modems
Discusses some basic troubleshooting of problems related to modems. This page is from "The PC Guide."
HardwareCentral
Resource site offering news and information about PC hardware elements. Includes timely feature articles and sections on optimization and troubleshooting.
Webopedia's "Did You Know...?" Section
Use this Webopedia knowledge section for an in-depth overview of specific technologies and occurrences in the areas of Computer Science, The Internet, and Computer Hardware and Software.
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