Seen here in 1964 are three eras of computer technology: the vacuum tube (at left) of the late-1940s and early-1950s, the transistor (middle) of the late-1950s and early-1960s, and the chip transistor (that little dot at right). At first, transistors, whose wire connector legs made them look like spiders, were wired with other components, such as resistors, on circuit cards to form logic and control elements of processors. But, starting with the IBM System/360 in 1964, circuits were closely combined on half-inch ceramic modules. The era of microelectronics had begun. (VV2124).