The product cycle is also a cycle of dependency. We don't just want the newest thing—we actually need it. The first commercial computers of the 1950s were mainframe systems. In a mainframe, a central terminal—sometimes as large as a room—houses processors, memory, and storage. Individual workstations connect to that central hub to tap into shared programs and databases. Over the decades, the systems grew increasingly powerful. Mainframes at large institutions or agencies can run multiple instances of an operating system at once. The everyday user, however, has no need for anything as large and expensive as a mainframe. At home, personal computers still rule.