Bill Gates spent his last day at Microsoft Friday; bidding a teary goodbye to the company he built into a global software colossus.
The Microsoft co-founder, 52, known for his boyish face and nerdy manner, will now focus on running the Bill & Melinda Gates Foundation, aimed at fighting disease, reducing poverty, and improving education around the world.
Gates began programming computers when he was 13 and a student living in the northwestern US state of Washington.
"Very early he demonstrated this really insatiable curiosity," his father, William Gates Sr., said of his son in a video interview posted on the Microsoft website.
"He became a voracious reader. We knew he was smart, he was academically gifted, but we didn't have any impression there was something world class going on in our living room necessarily."
Gates took his passion for knowledge to Harvard University in 1973. At Harvard Gates met Steve Ballmer, who became part of Microsoft and was promoted to chief executive in 2000.
Gates recalls being in Harvard Square when Allen showed him a magazine cover story about a computer advancement, and thinking "This is happening without us and we are going to miss it."
Gates, with the blessing of his lawyer father and teacher mom, left college after two years to start "Micro-soft" with Allen.
The duo bought the rights to existing computer software, modified it, got a copyright, and rechristened it Microsoft Disk Operating System (MS-DOS).
A key move by Gates was to focus on licensing software to computer makers in numerous "partnerships" that resulted in affordable machines being available to the masses.
Microsoft's slogan was "A computer on every desk and in every home" -- using, of course, its software.
Today more than 90 percent of the world's computers run on Microsoft software.
Gates eases into retirement ranked the third richest person in the world, behind US investor Warren Buffet and Mexican tycoon Carlos Slim.
Gates remains Microsoft's largest single shareholder and chairman of company's board of directors.
