Before he was an elder statesman of charity, Bill Gates was a hard-charging thrill seeker.

Microsoft cofounder Paul Allen has a memoir called "Idea Man" coming out today. In it, he reveals some amazing stories about his friend Bill Gates.

Early excerpts from the book portrayed Gates as a tough negotiator who talked Allen into receiving a smaller share of the company they founded together.

But the memoir also contains some lighter anecdotes about Gates in his childhood and the early days of Microsoft. If you're only familiar with Gates in his elder-statesman charity role, you may not recognize the hard-charging thrill seeker who built the most profitable tech company in history.