Hayes Microcomputer Products (English Wikipedia)

"Data Communication System from D.C. Hayes". Intelligent Machines Journal (10): 6. 25 June 1979. ISSN 0199-6649.
"Hayes Microcomputer Products, Inc". Computerworld. 15 (17). CW Communications: 42. April 27, 1981. ISSN 0010-4841. The 300 baud auto-dial/auto-answer Smartmodem had a suggested retail price of $279.
"Hayes Smartmodem". InfoWorld. 3 (14). InfoWorld Media Group: 9. July 20, 1981. ISSN 0199-6649. "The Smartmodem is the first in a series of products Hays planes to introduce in a standard stack-mount design."
Markoff, John (April 25, 1983). "Stand-alone Smartmodem 1200 from Hayes". InfoWorld. Vol. 5, no. 27. pp. 90–93. ISSN 0199-6649. "The Hayes Smartmodem 1200, which was introduced in the middle of 1982, ..." Price $699.
Markoff, John (10 October 1983). "BizComp's patent could raise retail price of modems". InfoWorld. p. 1.
Martin, James (15 December 1986). "Can firms fight 'jungle king'?". Computerworld. p. 94.
"Brief Notes". Computerworld. 20 November 1989. p. 113.

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US Expired 4387440, Michael Eaton, "Modem control device code multiplexing", issued 7 June 1983, assigned to Business Computer Corp
US Expired 4549302, Dale Heatherington, "Modem with improved escape sequence mechanism to prevent escape in response to random occurrence of escape character in transmitted data", issued 22 October 1985, assigned to Hayes Microcomputer Products and Telogy Networks

Kirksey, Kenneth (25 December 1991). "What You Need To Know About Modems". The immense popularity of the HST modems was partly due to the generous discount program U.S. Robotics offered to the BBS Sysops (SYStem OPerators).
Kirksey, Kenneth (25 December 1991). "What You Need To Know About Modems". p. Hayes Express 96.

Shannon 1999. Shannon, Victoria (7 January 1999). "The Rise and Fall of the Modem King". International Herald Tribune. Archived from the original on 17 December 2019. Retrieved 17 December 2019.{{cite news}}: CS1 maint: bot: original URL status unknown (link)

"Data Communication System from D.C. Hayes". Intelligent Machines Journal (10): 6. 25 June 1979. ISSN 0199-6649.
"Hayes Microcomputer Products, Inc". Computerworld. 15 (17). CW Communications: 42. April 27, 1981. ISSN 0010-4841. The 300 baud auto-dial/auto-answer Smartmodem had a suggested retail price of $279.
"Hayes Smartmodem". InfoWorld. 3 (14). InfoWorld Media Group: 9. July 20, 1981. ISSN 0199-6649. "The Smartmodem is the first in a series of products Hays planes to introduce in a standard stack-mount design."
Markoff, John (April 25, 1983). "Stand-alone Smartmodem 1200 from Hayes". InfoWorld. Vol. 5, no. 27. pp. 90–93. ISSN 0199-6649. "The Hayes Smartmodem 1200, which was introduced in the middle of 1982, ..." Price $699.