CUPERTINO (CBS News) — While Steve Jobs’ announcement that he was resigning as CEO of Apple may have come as a surprise to some, the company was already being run by the man tapped to replace him, according to most reports.

Tim Cook, the unflappable Alabaman, had been Apple’s chief operating officer since 2007, running its day-to-day operations, a role many expect him to keep as CEO. He had twice taken over CEO duties during Jobs’ recent medical leaves.

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While most insiders said Cook is not the “visionary” that Jobs is, nearly everyone credits him as being a kind of business-operations “maestro,” according to a 2008 Fortune magazine profile.

Cook earned an M.B.A. from Duke University, where he was a Fuqua Scholar, and a Bachelor of Science degree in Industrial Engineering from Auburn University, according to his official Apple biography. Prior to joining Apple, Cook had served in various executive roles at Compaq, Intelligent Electronics and IBM.

While Jobs and Cook are both known for their relentlessness, they largely operate in opposite ways, The New York Times reported.

Jobs is often described as mercurial and prone to outbursts, while Cook, who was raised in a small town in Alabama, is polite and soft-spoken. Whereas Jobs liked to focus on Apple’s products, Cook has largely delved into the minutiae of its operations.

>> Related Photo Gallery: Steve Jobs Through The Years

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Cook has earned credit and praise for cleaning up Apple’s once-faulty manufacturing, distribution, and supply apparatus in his roll as COO, according to the aforementioned Fortune profile.

After Cook joined Apple in 1998, there was one moment now part of the Cook lore that well-describes his leadership style, Fortune noted. At a meeting on Apple’s manufacturing and supply woes, Cook told the group “This is really bad. Someone should be in China driving this.”

A half-hour later, Cook reportedly looked at one of his key operations executives and asked: “Why are you still here?” The executive stood up, drove to the airport, and flew to China without a change of clothes nor a return ticket.

Cook is unmarried, known for his serious demeanor, and not known to socialize much, the Times indicated, adding that “his major passion outside of Apple is Auburn football. Former colleagues also described him as a fitness enthusiast who seems to live on energy bars. He is a hiker and a cyclist, who frequently gets up at 5 a.m. to exercise — and to begin e-mailing his underlings.”

At Apple, Cook has earned a reported $156.2 million, including salary, bonuses and gains from stock awards, according to Equilar, a company that analyzes executive compensation. In addition, he holds Apple stock valued at about $140 million.

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