We are now in the third stage of the industrial revolution. The first involved machines which extended human muscle; the second used machines to extend the human nervous system (radio, television, telephones); the third is now utilizing machines which extend the human mind-computers. About half of all service workers (43 percent of the labor force by 2000) will be involved in collecting, analyzing, synthesizing, structuring, storing, or retrieving information... By 1995, 80 percent of all management will be "knowledge workers."