The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
The modem allows for the transfer of computerized information via channels such as cables, radio aerial arrays or satellites. The information is modulated into amplitude, frequency or phase, which allows for the transmission. The modem contains both a modulator for transmitting information and a demodulator for receiving information. The term "modem" is short for modulator-demodulator.
One of the first known modems was produced for IBM in 1954 and called the Data Transciever. A similar device was developed around the same time at the MIT Lincoln Laboratory and Bell Telephone Laboratories for the Department of Defense.
Early modems operated at a speed of 1200 baud (bits-per-second). By the 1970s that number had been increased by 700%, to 9600 baud, although the standard through the 1980s was only 2400 baud. By 1991, the standard had been increased to 14.4 kilobits (14,400 baud). By the mid-1990s, modems were operating at speeds of 28.8 kilobits and higher. By this time, internal modems were standard equipment on most full-sized computers. Modems for laptop, notebook and handheld computers were available in a credit-card sized unit; some of these units could operate using a cellular phone.
Also by this time, modems had been developed that allowed for voice as well as data transmission, although not at the same time. Simultaneous voice and data (SVD) and digital SVD (DSVD) units, which allow transmission of both voice and data at the same time, also were under development, as were integrated services digital network (ISDN) units that could transmit video.