In a blog entry published Tuesday celebrating his friendship with his co-founder, Paul Allen, who died on Oct. 15 at age 65, Bill Gates remembered the moment Microsoft leapt into being.

The memory dates back to 1975. The two men thought they’d already missed the microcomputer revolution, and in fact, they didn’t realize until later how ahead they had been. Gates credits Allen with understanding that far better and far earlier than he did.

Allen and Gates both lived in the Boston area, Allen working as a programmer for Honeywell after dropping out of Washington State University, and Gates attending Harvard. Gates recalls Allen finding him and taking him urgently to a newsstand to show him the January 1975 issue of Popular Electronics.

The cover depicted the Altair 8800, an unimpressive box covered with switches to modern eyes, but which sparked the PC revolution. Gates recalled that Allen said, “This is happening without us!”

Despite the cover calling it a “minicomputer,” the Altair had a powerful microprocessor in it. An editorial inside trumpeted, “The Home Computer Is Here!” For $400 ($1,900 in 2018 dollars), you could purchase and assemble a kit that gave you a shocking amount of computational power—especially when the next fastest device available to consumers and hobbyists was a scientific calculator. Beyond that, only businesses and colleges had minicomputers or mainframes, both expensive, with restricted access, and shared with many other users.

On the basis of that magazine cover and Allen’s enthusiasm, Gates left college. The next year the two founded Micro-Soft. (It later lost the hyphen.)

Gates’ remembrance of Allen concludes with strong emotion: “Paul deserved more time in life. He would have made the most of it. I will miss him tremendously.”