NEW YORK — In a forthcoming memoir, Microsoft Corp. co-founder Paul Allen details tensions in his relationship with Bill Gates, including a scene from 1982, when he overheard Gates talking to current CEO Steve Ballmer about reducing Allen’s stake in the company while he was undergoing cancer treatment.

“Unable to stand it any longer, I burst in on them and shouted, ‘This is unbelievable! It shows your true character, once and for all.’ I was speaking to both of them, but staring straight at Bill,” writes Allen in thebook, a part of which was published by Vanity Fair magazine online this week. (Read article here.)

The book, “Idea Man,” will be published April 19 by Portfolio/Penguin Group.

In the published excerpt, Allen chronicles the first time he and Gates met, in 1968. Allen was in the 10th grade and Gates, “all arms and legs and nervous energy,” in the eighth.

“You could tell three things about Bill Gates pretty quickly. He was really smart. He was really competitive; he wanted to show you how smart he was. And he was really, really persistent,” writes Allen, who left Microsoft in 1983.

From there on, Allen paints Gates as an ultra-focused micro-manager who expects nothing short of total dedication from his employees. Allen’s memoir says Gates slowly tried to lower Allen’s stake in the company while increasing his own, which may remind readers of a movie about more recent founding story, that of Facebook.

“From the time we’d started together in Massachusetts, I’d assumed that our partnership would be a 50-50 proposition. But Bill had another idea,” writes Allen, adding that he later agreed to a 60-40 split of Microsoft, thinking it might be fair. Not long after, Allen writes that changed to 64-36.

In a statement, Bill Gates said “while my recollection of many of these events may differ from Paul’s, I value his friendship and the important contributions he made to the world of technology and at Microsoft.”

Microsoft, where Ballmer is now CEO, declined to comment.

Discord among co-founders of successful companies are common — about who should get what, who did the most work and ultimately who was responsible for the idea that led to the world-transforming product and the piles of money.

The founding story of Facebook — or at least one side of it — become one of Hollywood’s most talked-about movies of last year. In “The Social Network,” which Facebook dismisses as fiction, the younger Mark Zuckerberg is portrayed as an arrogant, socially awkward kid who ripped off the idea of Facebook and sold out his best friend to get ahead.

Judging by the Vanity Fair excerpt, “Idea Man” isn’t all Microsoft high drama. Allen also writes about a dinner he had with Gates where Gates eats roast chicken with a spoon, and the time he gives Allen’s wife, Rita, some fashion advice: “basically, to buy all your clothes in the same style and colors and save time by not having to match them. For Bill, that meant any sweater that went with tan slacks.”

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