to the passage below and then answer the question afterwards in the same language as the passage: Passage: In 1991, Apple introduced the PowerBook, replacing the "luggable" Macintosh Portable with a design that set the current shape for almost all modern laptops. In October 1990, Apple introduced System 7, a major upgrade to the operating system which added color to the interface and introduced new networking capabilities. It remained the architectural basis for the Classic Mac OS. The success of the PowerBook and other products brought increasing revenue. For some time, Apple was doing incredibly well, introducing fresh new products and generating increasing profits in the process. The magazine MacAddict named the period between 1989 and 1991 as the "first golden age" of the Macintosh. Apple the Apple II series was too expensive to produce and sales away from the low-end Macintosh. In October 1990, Apple began the Macintosh Lintosh, and computer Apple advised that Apple to promote Apple in 1993.
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