Resumen
Unlike the steady predictable hardware price/performance improvement described by Moore's law, there has been no such year to year progress in the user interface design. Instead, the history of user interfaces can be characterized using evolutionary biologist Steven Jay Gould's notion of punctuated equilibrium, long periods of stability interrupted by rapid change. People can identify four separate generations characterized by four distinguishable interface styles, each lasting for many years and optimized to the hardware available at the time. In the first period, the early 1950s and 1960s, computers were used in batch mode with punched card input and line-printer output. The second period in the evolution of interfaces , early 1960s through early 1980s was the era of timesharing on mainframes and minicomputers using mechanical or glass teletypes. During the 1980s, when desktop productivity tools began to be used by millions of people, it was recognized that above some minimal threshold of functionality and performance, the most important predictor of an application's success was its ease of use.