To convert a digital signal to an analog one, the modem generates a carrier wave and modulates it according to the digital signal. The kind of modulation used depends on the application and the speed of operation for which the modem is designed. For example, many high-speed modems use a combination of amplitude modulation, where the amplitude of the carrier wave is changed to encode the digital information, and phase modulation, where the phase of the carrier wave is changed to encode the digital information. The process of receiving the analog signal and converting it back to a digital signal is called demodulation. The word "modem" is a contraction of its two basic functions: modulation and demodulation.

They sold the first Hayes modem products to computer hobbyists in April of 1977 and founded D.C. Hayes Associates, Inc., the company known today as Hayes Corp., in January of 1978. Hayes quality and innovation resulted in performance enhancements and cost reductions that led the industry in the conversion from leased line modems to intelligent dial modems - the PC Modem.

Hayes-Compatible, in computer science, an adjective used to describe a modem that responds to the same set of commands as a modem manufactured by Hayes Microcomputer Products, originators of the de facto standard for microcomputer modems.

RELATED INFORMATION:
History of Computing   from The Great Idea Finder

ON THE WEB:
Zoom Telephonics, Inc.
This company acquired most of the modem assets of Hayes Corporation.
(URL: www.zoom.com/news.shtml)
The Rise and Fall of the Modem King
Dennis C. Hayes begins selling personal computer modem products to computer hobbyists. Initially, the modems are boards for the S-100 bus, and later for the Apple II. International Herald Tribune. Article by Victoria Shannon.
(URL: timeline.textfiles.com/1977/)
CRN Industry Hall Of Fame
As USIIA chairman, Hayes advocates effective Internet policy, a role born from his invention of the PC modem in the late 1970s. CMP article by Michele Pepe.
(URL: www.crn.com/)
Hayes Compatible
There was a time when Hayes compatible meant something.
(URL: www.pcwebopaedia.com/TERM/H/Hayes_compatible.html)
Modem Standards
The organization that now sets modem standards is the International Telecommunication Union.
(URL: www.itu.int/home/index.html)
Computer History
Timeline of computer history from BC to the present. Presented by Computer Hope, free help for computer users.History for 1960 - 1980
(URL: www.computerhope.com/history/196080.htm)

HOW IT WORKS:
How Modems Work
From the popular How Stuff Works Web site by Marshall Brain. Lots of COOKIES and POP-UP ADS at this site.

DID YOU KNOW?

• 1978 -- Dennis C. Hayes and partner Dale Heatherington, working on Hayes’ dining room table, develop first personal-computer modem and formed a company.
• 1985 -- Hayes annual sales hit $120 million as popularity of home computers grows.
• 1988 -- Hayes and first wife Melita divorce after six years of marriage.
• 1994 -- Hayes Microcomputer files for Chapter 11 bankruptcy reorganization.
• 1996 -- Company emerges from Chapter 11.
• 1997 -- Company merges with Access Beyond of Gaithersburg, Md.
• 1998 -- Hayes Corp. files for Chapter 11.
• 1999 -- January 6, Hayes shuts down Its operations.
• 1999 -- April. 7, Zoom Telephonics Acquires Hayes Modem Assets Source: Hayes Corp