The megastars in the IT industry over the past four decades are easy to name. The accomplishments of Bill Gates, Steve Jobs, Scott McNealy, Larry Ellison, Linus Torvalds and others are well known. But clearly there have been many more who have helped turn IT into the ubiquitous corporate necessity it is today. Here are those who deserve broader recognition for IT's global success.

Why: Changed a sleepy vertical application company into a diversified $1.5 billion software industry powerhouse. Bartz became president, CEO and chairman of Autodesk in 1992 after rising through the ranks of Digital Equipment Corp. and Sun Microsystems Inc. Her favorite saying: "You have only one job in this life, and that is to be a great ancestor."

Why: Invented the electronic spreadsheet with the introduction of VisiCalc in 1979, while working on his MBA at Harvard. Written in Basic on an Apple II personal computer, VisiCalc continued to ship first on Apple instead of IBM PCs, which helped Lotus 1-2-3 quickly eclipse the breakthrough software.

Why: Father of the relational database with his seminal 1970 paper, "A Relational Model of Data for Large Shared Data Banks." He first went to work for IBM in New York in 1953. He devised his famous 12 rules for what makes data relational in 1985. Codd died at the age of 79 in 2003, leaving behind a $13 billion market.

Why: Creator of the packaged software market. He led a company that could claim many industry firsts: first packaged application, first report writer software, first database to seriously compete with IBM on mainframes, and first pure software company to go public. He sold the company to Computer Associates in 1989.

Why: Co-inventor with Martin Hellman of public key encryption software, with the publication of their paper "New Directions in Cryptography." Although Diffie holds a bachelor's degree in science from MIT and an honorary doctorate from the Swiss Federal Institute of Technology, he never graduated from high school.

Why: Coined the term "data warehouse" in 1990 and is considered the father of the $28 billion industry. Inmom defined a data warehouse as a place where information is subject-specific, integrated, time-dependent and nonvolatile, i.e. more data can be added, without changing old data. A prolific writer, Inmon has published more than 650 articles and 46 books -- so far.

Why: Iconic business maverick who blazed trails to deliver IT services to corporate users. Perot took a $1,000 loan in 1962 and parlayed it into a $2.5 billion payoff when he sold EDS to General Motors Corp. in 1984. He snagged more than 8 million votes in a U.S. presidential bid for the Reform Party in 1996.

Why: Helped create and document numerous standards and protocols for the Internet, including TCP/IP, SNMP and DNS. He is hailed as "the shepherd of the Internet." A firm believer in the value of content over presentation style, Postel never used PowerPoint in his career.

Why: Developed the C programming language, the foundation for the portability of Unix to different hardware systems. Ritchie followed in his father's footsteps and joined Bell Labs in 1967, quickly aiding in the creation of Unix in 1969 with Ken Thompson, with whom he shares a Turing Award.

Why: Led the IBM team in 1959 that gave us the first floppy disk, the 8-in., 5MB Ramac. While at IBM, he also oversaw the creation of the 50MB disk system for the first electronic reservation system, Sabre. He founded Seagate in 1979, which gave us the 5 1/2-in. disk drive that helped fuel the PC revolution.