Bill Gates famously dropped out of Harvard University during his junior year — but in his new memoir, Source Code, he’s opening up about getting into trouble with the school’s Administrative Board as a sophomore.

Gates was studying for spring finals when he received a phone call from a school official telling him, “I want to see you in my office tomorrow.”

The billionaire philanthropist writes that, right away, he knew what the problem was: his computer usage.

During the meeting, Gates learned that he’d logged 711 hours at the school’s Aiken Computation Laboratory, which was funded by the U.S. Department of Defense.

An even bigger issue? He’d brought two “unauthorized people” — one of whom was future Microsoft co-founder Paul Allen, who was never a Harvard student — to the lab to work on a “commercial project” for computing.

Eventually, Gates had to hand over his key to the computer center and learned that he was being reported to the school’s Administrative Board.

It was only two days later that Gates realized exactly what was at stake.

As his senior tutor explained, according to Source Code, “in the worst case, the board couple expel me from Harvard, and if they found my actions particularly grievous, they would expunge my record.”

Faced with the prospect of potentially getting kicked out of college, Gates writes, he sent a letter to the Administrative Board, which was both a “defense of my actions,” a “critique” of the computer lab — which didn’t have much oversight at the time — and the fact that he believed microcomputers were the future.

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After his dad suggested he “be more conciliatory,” he went on to conclude his letter with more apologies.

One week later, Gates heard that the Administrative Board had made a decision about what to do.

“They voted to ‘admonish me’ for improper and unauthorized use of the lab,” Gates writes, which meant that he got off without even a punishment.

Speaking with PEOPLE about his memoir, Gates was asked why it has taken so many years for him to share this story.

“I don’t know,” he says, noting that it ended up not being “that big a deal” — and that it’s something that only comes up “if you’re going to go into a lot of detail.”

“I try not to distort things,” he insists, bringing up his 1977 arrest for speeding in Albuquerque, N.M., as an example, which ended with Allen bailing him out.

Gates says that he has talked about getting “a lot of tickets” and says that, admittedly, he does think he’s brought up what happened at Harvard during some school-related “historical” events.

Ultimately, he adds, “I had my ups and downs, and that one was more of a misunderstanding.”

Source Code is out now.