Although he’s not quite the household name as Bill Gates, Microsoft co-founder Paul Allen is undeniably an incredibly influential technology innovator. But while Allen and Gates revolutionized the computer software landscape together — and become billionaires in the process — there were times when their partnership wasn’t as solid as it appeared to outsiders.

Allen’s new memoir Idea Man chronicles the development of Microsoft as well as the unique relationship between the company’s two founders. While the two started the company as friends, Allen says Gates’ competitive nature created an environment that was like “being in hell.” While he was battling Stage 4 lymphoma, Gates allegedly plotted to squeeze Allen out of the company he founded, which led to the lowest point in their close but contentious relationship.

In a recent interview with 60 Minutes‘ Lesley Stahl, Allen discusses his motivations for writing the tell-all memoir, while stressing that “it’s not about [revenge].” He also discusses what he has been involved in outside of the renowned software conglomerate that he helped create.

Check out the full 60 Minutes segment below.