Microsoft co-founder Bill Gates used to memorize employees’ license plate numbers so that he could keep track of when they were arriving at work and leaving.

Gates, who is now co-chair of the Bill and Melinda Gates Foundation, described his intense management style from Microsoft’s early days during an interview on the BBC Radio 4 program “Desert Island Discs.”

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"I had to be a little careful not to try and apply my standards to how hard [others at the company] worked. I knew everybody's licence plate so I could look out the parking lot and see, you know, when people come in,” he said. “Eventually I had to loosen up as the company got to a reasonable size."

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Gates was 19 when he dropped out of Harvard to start Microsoft with Paul Allen in 1975. He stepped down as the CEO of the software giant in 2000 and stepped down as the company’s chairman in 2014.

The philanthropist also described his relationship with Apple co-founder and tech icon Steve Jobs during the radio interview.

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"Steve really is a singular person in the history of personal computing in terms of what he built at Apple,” he said. “For some periods, we were completely allies working together - I wrote software for the original Apple II. Sometimes he would be very tough on you, sometimes he'd be very encouraging. He got really great work out of people.”

Gates also described how his relationship with Jobs changed over the years. The former Apple CEO lost his battle with pancreatic cancer in 2011.

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"In the early years, the intensity had always been about the project, and so then [when] Steve got sick, it was far more mellow in terms of talking about our lives and our kids,” he said. “Steve was an incredible genius, and I was more of an engineer than he was. But anyway, it was fun. It was more of a friendship that was reflective, although tragically then he couldn't overcome the cancer and died."

On “Desert Island Discs” guests are invited to choose the eight records that they would take with them to a desert island. Among his selections, Gates chose “Under Pressure” by David Bowie and Queen, Jimi Hendrix’s “Are You Experienced” and “How Can Love Survive” from “The Sound of Music.”