Don Valentine, the longtime founding venture capitalist at Sequoia Capital who led investments in Cisco Systems Inc., Oracle Corp., Electronic Arts Inc. and many other iconic Silicon Valley firms, died today at age 87 at his home in Woodside, California.

As Sequoia itself said in a post today on its site, “Remembering Don Valentine,” he’s responsible as much as anyone for what the explosion of entrepreneurial activity in what became widely known as Silicon Valley. Born in New York in 1932, he started in Southern California’s aerospace industry before moving up to the San Francisco peninsula to join the seminal chipmaker Fairchild Semiconductor.

He later became founding vice president of sales and marketing at National Semiconductor, where he started making personal investments in startups. Joining with mutual-fund manager Capital Group, he started Capital Management Services with a now-quaint $3 million fund in 1974. Among its investments: Atari and Apple Computer, on whose boards Valentine served. The firm became Sequoia Capital.

Sequoia invested in a long list of long-lived companies: Oracle, LSI Logic, Linear Technology, Network Appliance and Cisco, among others.

Unlike some of his colleagues and certainly many of the founders and executives at his portfolio firms, Valentine largely shunned the spotlight.

Among my few interviews with him, the one I remember best was by phone, when researching a story during one of Silicon Valley’s periodic downturns in 2003. For the BusinessWeek story that ultimately became “The Quest for the Next Big Thing,” I sought to find out what new technologies or trends he was hoping to capitalize on, and he clearly didn’t want to reveal that to the wide world. He spent much of the interview instead griping about what caused the downturn: “extraterrestrials,” by which he meant Valley outsiders and amateurs.

When I pointedly asked him, “What do you think is the next big thing?” he paused for several beats and then said, very slowly, as if to a child, “I wouldn’t tell you that if you were my mother.” And that was pretty much the end of the conversation.

Valentine, and his firm generally, became known as tough taskmasters, unforgiving to founders who weren’t cutting it, though it was hardly alone in that quality among VCs. Unlike many VC firms that swear the team is the most important factor in a company’s success, Sequoia at least while Valentine was there wasn’t shy about trumpeting the paramount importance of ideas and products and didn’t hesitate to find new management for a company and even invested in firms that were rivals to portfolio firms if they were promising.

But in later years, as he stepped away from active involvement with Sequoia, he appeared more open with advice, appearing at some industry conferences such as TechCrunch Disrupt (pictured). According to Sequoia, he “favored green ink, never drank coffee, listened carefully, understood the virtues of silence, built the foundation on which so many have the good fortune to stand, and insisted that the ultimate test for every startup was a thoughtful answer to his perpetual question about its quest, ‘Who cares?'”

Valentine is survived by his wife of 58 years, Rachel, three children and seven grandchildren. A celebration of his life is expected to be announced later.

Photo: JD Lasica/Flickr