In 1977, three new microcomputers appeared on the scene that broke free from the industry’s hobbyist roots: the Apple II, the Commodore PET, and the Tandy/Radio Shack TRS-80. Much later, in the 1990s, journalists and historians began reverently referring to this group as “the Trinity.” Though all three machines had different origins and different trajectories (Apple, for example, appeared in 1978 to be an also-ran before rising to eclipse all of its rivals), the distinctiveness of the 1977 gener...