Paul Allen, Microsoft co-founder, arrives at Time Magazine's 100 Most Influential People in the World dinner on May 8, 2008 in New York. (STAN HONDA/AFP/GETTY IMAGES)

Allen and Gates co-founded “Micro-Soft” in 1975. The two men have known each other since they were in grade school and their relationship has always been perceived as a cordial one.

But Allen’s new book paints a different picture of the partnership and includes allegations that Gates plotted to take Microsoft shares from Allen while the latter was undergoing cancer treatment.

An excerpt of Allen’s book run by Vanity Fair on Wednesday paints Gates — and current Microsoft CEO Steve Ballmer — in an unflattering light. Gates particularly comes off as a ruthless businessman with no consideration for his co-workers.

According to the Wall Street Journal, the book has already caused some controversy among Microsoft’s earliest employees. Several people who know both Allen and Gates have reportedly questioned the accuracy and interpretation of some events in Allen’s book.

Allen is not doing interviews before the book, “Idea Man,” is published on April 19.

Gates responded to the book with a written statement to the Journal. “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,” he wrote.