It seems obvious now: People are the “killer app” for computers. Computers are less about computing and much more about communication, connection and community. Facebook, LinkedIn, YouTube, email, instant messaging, multiplayer games and discussion forums—today’s most popular uses of computers are all about human interaction. It wasn’t always so, nor was it always so obvious. In “The Friendly Orange Glow,” author and technology entrepreneur Brian Dear tells the fascinating story of Plato, an educational computer system developed during the 1960s and 1970s that was used by tens of thousands of students. Plato astonishes in multiple ways. Technologically, it was far ahead of its time, offering its users the flat-panel graphical displays, touch screens and collaborative apps we take for granted today. Socially, its users formed some of the earliest online communities, dozens of years before they would become commonplace. Historically, it is virtually unknown; it is as if, Mr. Dear writes, “an advanced civilization had once thrived on earth, dwelled among us, built a wondrous technology, but then disappeared as quietly as they had arrived.” Mr. Dear traces Plato’s origins to the 1950s, starting with the psychologist B.F. Skinner’s quest for an “automatic teacher” that would allow students to pace themselves and receive instant feedback—a quest that picked up steam with the 1957 launch of the Soviet Sputnik satellite and the ensuing U.S. “educational emergency.” People soon realized that this newfangled thing called a “computer” might be the perfect teacher: While expensive, it might, with the right programming and remote terminals, provide teaching precisely tuned to students’ needs. Plato—Programmed Logic for Automatic Teaching Operations—began its life in 1960 at the University of Illinois’s Control Systems Laboratory, a defense lab run by physicists and engineers. Plato’s fathers were the lab’s director, Daniel Alpert, and the project lead, freshly minted Ph.D. Don Bitzer. Mr. Dear likens them respectively to a “venture capitalist” and a “whiz-kid start-up founder.” Over the next two decades Mr. Bitzer led a crew through numerous challenges. How would they build a system capable of supporting multiple users? How would instructors create lessons without having to become expert computer programmers? How would the remote computer terminals work? How could they be made cost-effectively? Their novel solution to this last problem gives the book its title: The Plato team developed the flat-panel plasma display—which at the time could only produce one color. As a result, Plato terminals bathed their users in a distinctive orange light that users came to call the “Friendly Orange Glow.” Mr. Bitzer brought a unique management style, one that welcomed help from just about any source—including high-school kids. The Plato lab’s openness was legendary, with an ethos that Mr. Dear summarizes as, “You never knew who was the next Einstein, so encourage everyone to be the next Einstein and increase the odds that the next Einstein would reveal himself.” The result was that key parts of the Plato system were written by users in their late teens and early 20s—the youngest being a 12-year-old who attended school across the street. (The university was unable to pay him until he turned 14 due to child-labor laws.) Foreshadowing the philosophy of the internet years later, Plato was what today we would call an open platform. Mr. Dear says: “If you wanted to build a lesson on PLATO that reflected your own pet theory, you should be able to go right ahead, as long as other authors could create their own lessons that followed other theories.” By the early 1970s, Plato was well on its way to achieving its goals, connecting thousands of students across the country with graphical displays and touch screens and providing online lessons ranging from basic arithmetic and reading to advanced subjects like biology and chemistry. It was around this time that something interesting happened: Its denizens began to adapt Plato not just for education but for communication. A program called Discuss, for example, allowed users to post messages of up to 10 lines of text. It was soon used for organizing an attempt to impeach President Nixon, earning Mr. Bitzer a call from one of his government funding agencies. Another program, Talkomatic, allowed instant messaging between users. Discuss was supplanted by Notes, a more sophisticated discussion system that would grow to have hundreds of topics. Notes was quickly followed by Personal Notes, an email system. Plato even boasted its own electronic newspaper. And then there were the games. So many games: Spacewar, Mazewar, Moonwar, Dogfight; dungeon adventures like Avatar, “dnd” and Moria; and Empire, a graphical “Star Trek” game. Not only did they support multiple users who could play with or against one another, they allowed users to communicate inside the game via instant messages—all this as early as the mid-1970s. This connectedness yielded what Mr. Dear accurately terms “the dawn of cyberculture.” Plato’s close-knit community became a nexus of friendship, romance and feuds. Some users were driven to great lengths to get their Plato fix; Mr. Dear describes students hiding in the walls of a classroom behind loosened partitions so as to be able to sneak back in and use Plato terminals undisturbed after closing time. The community expanded throughout the 1970s and early 1980s as other institutions installed their own Plato mainframes and linked them together. Sensing a business opportunity, industry giant Control Data Corp. licensed Plato from the University of Illinois in the mid-1970s. Sadly, this initially promising attempt at commercialization foundered because of bad luck, poor marketing decisions and a failure to comprehend the onrushing wave of microcomputers such as the Apple II. In some alternate universe, Plato might have been AOL, but 10 years earlier. By the mid-1980s the system had become outmoded, and the University of Illinois’s Plato lab was shut down in 1993. Plato’s echoes can still be heard, faintly, in such places as “Notes,” IBM’s collaborative software platform (which traces its inspiration directly to Plato), to say nothing of the success of various computer games, many of which were written by former Plato users and programmers. Mr. Dear guesses that he spent about 11 years of solid work on his book over more than 30 years. His diligence shows. Thanks to his meticulous research and conversational writing style, “The Friendly Orange Glow” is an enjoyable and authoritative treatment of an important piece of our social and technological heritage.