Robert W. Taylor, who helped shape our modern connected computer world, died Thursday at 85 at his home in Woodside.

Mr. Taylor died of complications of Parkinson’s disease, his son Kurt said.

The Internet, like many inventions, was the work of many inventors. But perhaps no one deserves more credit for that world-changing technological leap than Mr. Taylor.

The seminal moment of his work came in 1966. He had just taken a new position at the Pentagon — director of the Information Processing Techniques Office, part of the Advanced Research Projects Agency, known as Arpa — and on his first day on the job it became immediately obvious to him what the office lacked and what it needed.

At the time, Arpa was funding three separate computer research projects and using three separate computer terminals to communicate with them. Mr. Taylor said, No, we need a single computer research network, to connect each project with the others, to enable each to communicate with the others.

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“I went to see Charlie Herzfeld, who was the head of Arpa, and laid the idea on him,” Mr. Taylor recalled in an interview for this obituary. “He liked the idea immediately, and he took a million dollars out of the ballistic missile defense budget and put it into my budget right then and there.” He added, “The first funding came that month.”

His idea led to the Arpanet, the forerunner of the Internet.

A half-decade later, at Xerox’s storied Palo Alto Research Center, Mr. Taylor was instrumental in another technological breakthrough: funding the design of the Alto computer, which is widely viewed as the forerunner of the modern personal computer.

Mr. Taylor even had a vital role in the invention of the computer mouse. In 1961, at the dawn of the Space Age, he was about a year into his job as a project manager at NASA in Washington when he learned about the work of a young computer scientist at Stanford Research Institute, later called SRI International.

The scientist, Douglas Engelbart, was exploring the possibilities of direct interaction between humans and computers. Mr. Taylor decided to pump more money into the work, and the financial infusion led directly to Engelbart’s invention of the mouse, a computer control technology that would be instrumental in the design of both Macintosh and Microsoft Windows-based computers. (Engelbart died in 2013.)

“Any way you look at it, from kick-starting the Internet to launching the personal computer revolution, Bob Taylor was a key architect of our modern world,” said Leslie Berlin, a historian at Stanford’s Silicon Valley Archives.

At NASA, as the new Kennedy administration was putting the nation on a path to the moon, Mr. Taylor met and became a friend and protege of J.C.R. Licklider, a psychologist and computer scientist who had written a pioneering paper titled “Man-Computer Symbiosis.”

As much as any single document, the paper became a road map for the development of the Internet and the personal computer, as well as spectacular advances in artificial intelligence and robotics.

Robert William Taylor was born on Feb. 10, 1932, in Dallas and was adopted 28 days later in San Antonio by the Rev. Raymond and Marie Taylor, a Methodist minister and his wife. Growing up, he moved frequently as his father was assigned to different parishes. He often spent summers in Austin with an aunt and uncle.

After earning a bachelor’s degree from Southern Methodist University in Dallas, he went on to do graduate work at the University of Texas at Austin. It was there, while working on his master’s thesis in experimental psychology, that he developed a fascination with new forms of human-computer interaction.

His thesis research focused on how the ear and the brain localize sound. When he came to analyzing his data, he took it to the university’s computing center, where he met a staff member in a white coat who, working behind a protective glass wall, helped operate the center’s mainframe computer. The staff member showed him the laborious process of entering his data and his program onto computer punch cards, the standard of the era.

“I was appalled,” Mr. Taylor recalled years later during an interview at the university, “and after I thought about it for a while, I was angry.” The data entry process, he said, was “ridiculous.”

“I thought it was insulting,” he added.

He left the center, went back to his laboratory and used a desktop calculator instead.

He knew, he said, that the calculator “could manipulate symbols — it used high voltages and low voltages to represent 1s and 0s — and that 1s and 0s could be combined to represent letters, and letters could be combined to represent text, and text could be combined to represent knowledge.

“Why couldn’t computers do that?”

Mr. Taylor left the Pentagon in 1969 and taught for a year at the University of Utah before joining the newly formed Xerox Palo Alto Research Center, or PARC, in California. There, he joined a small group of researchers who were refining many of the technologies that had been pioneered by Engelbart at the Stanford Research Institute as well as creating new ones, including graphical personal computing.

Mr. Taylor’s team of researchers built the prototype personal computer the Alto, and another group, led by Alan Kay, added a software system that pioneered the desktop metaphor, in which documents are represented by graphical icons on the computer display.

That technology, in turn, became the inspiration for Apple’s Lisa and Macintosh computers and for Microsoft’s Windows software.

The laser printer was also invented at PARC, and, besides generating profit for Xerox, it would play an important role in the “office of the future” ideas that were being explored by Mr. Taylor’s group.

It was Steve Jobs, however, who profited the most when Xerox management allowed him to visit with Mr. Taylor’s group at the Palo Alto center. Jobs, drawing on ideas he encountered there, went on to be the first to successfully commercialize the new style of computing.

Similarly, Charles Simonyi, a young software designer who developed an early word-processing software program for the Alto, took many of the PARC ideas with him when he joined Microsoft.

Toward the end of his career, in the 1990s, Mr. Taylor created and ran the Digital Equipment Systems Research Laboratory in Palo Alto, which helped pioneer the Alta Vista Internet search engine.

Besides Kurt, Mr. Taylor is survived by two other sons, Erik and Derek, and three grandchildren. His marriage to Joanne Honnold ended in divorce.

John Markoff is a New York Times writer.