Microsoft co-founder Paul Allen has claimed Bill Gates was "scheming to rip me off" over a share of the company during the time Allen was receiving treatment for cancer in the 1980s.
Allen is about to release his memoirs in a book, and Vanity Fair magazine has published an extract. The Vanity Fair portion of the book contains potentially damaging allegations about the way Gates treated Allen during his illness and the way he conducted business at the company. Gates has said his recollections may "differ".
Allen wrote in the book that while he had assumed the two founders would split ownership of Microsoft 50/50, Gates had argued he should take 60 percent as he claimed to have done the most work on their first commercial software programme. Allen had agreed to this split, but then Gates reportedly later argued for 64 percent. Allen again let him have his way.
Allen stated: "I'd been taught that a deal was a deal and your word was your bond. Bill was more flexible; he felt free to renegotiate agreements until they were signed and sealed."
Gates has so far declined to comment on specific claims in the book but has made a general statement about its publication. He 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."
And casting doubt on Gates' business dealings with him, Allen claimed Gates planned to offer better terms to lure Steve Ballmer to the company than the two founders had originally agreed. Allen said he only found out from a letter seen by another employee in the company's word-processing system.
The two had agreed to give Ballmer five percent equity in Microsoft to get him to join them, but Gates had offered Ballmer 8.75 per cent behind Allen's back, Allen wrote. This time however, Allen insisted, he didn't back down, and Gates instead gave Ballmer the extra 3.75 percent out of his own portion of the company.
Another potentially damaging allegation is that when Allen was passing Gates' office he overheard Gates and Ballmer complaining about his declining contribution to the company during his cancer treatment in 1982. He claimed they were discussing ways to dilute his shareholding in the company. Before this incident happened Allen had suggested he might well leave Microsoft to start his own company.
He stormed into the office after hearing what they were talking about, according to the book. Both Gates and Ballmer later apologised and urged him to stay with the company.
Allen said of the incident: "I helped start the company and was still an active member of management, though limited by my illness, and now my partner and my colleague were scheming to rip me off. It was mercenary opportunism, plain and simple."
Allen left Microsoft in 1983 but his involvement in setting up the company has still meant he has remained one of the richest men in the world, with a Forbes estimated wealth of $13.5bn.
Allen, 58, is now fighting another bout of cancer. His book, "Idea Man", is to be published this April by Portfolio.