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Cloud computing might seem like a modern convenience, but its roots lie in the timesharing computers developed at MIT in the 1960s.

Project MAC was directed by Italian-American computer pioneer Robert Fano, born on Nov. 11, 1917. Funded by the U.S. Department of Defense’s Advanced Research Projects Agency (better known as ARPA) and the National Science Foundation, Project MAC’s innovations made it feasible for corporations to invest in computer technology. Before timesharing, it simply wasn’t cost-effective to purchase a humongous mainframe computer that could only serve one user at a time.

How timesharing computing worked

The computer scientists working under Fano on Project MAC—most notably Fernando José Corbató—developed the concept of timesharing, in which multiple people could simultaneously use one mainframe computer through the assignment of “timeshares.” At its core, timeshare computing relied on the inevitable breaks humans must take: You enter a large amount of data, and then you must stop and think about your next move. That “break” constituted valuable time another user could be entering data.

Timesharing solved computer “bottlenecks,” as Corbató explains in this 1963 WGBH program. (For Fano’s take, watch this 1985 lecture.) Six months after Project MAC’s inception, 200 users from 10 MIT departments accessed the same computing system.

Fano’s prescience didn’t stop with timesharing. He was also an early advocate of open-source computing, considering computing a utility similar to water or electricity, and he pondered questions of digital ethics. When Fano died in 2016, MIT published an obituary quoting a paper Fano co-wrote with Corbató in which they asked: “One must consider the security of a system that may hold in its mass memory detailed information on individuals and organizations. How will access to the utility be controlled? Who will regulate its use?”

Tech Time Warp is a weekly feature that looks back at interesting moments and milestones in tech history.

Photo: Everett Collection/

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Kate Johanns

Posted by Kate Johanns

Kate Johanns is a communications professional and freelance writer with more than 13 years of experience in publishing and marketing.

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