说明：  现在的微型计算机系统一般都采用了总线结构，总线结构的特点微机各部件之间以 及微机与外设之间使用一组公共的的信号线，CPU 可以通过总线和各个部件交换数据
(Micro-computer system is now generally used bus architecture, bus structure is characterized by computer as well as between the various components between the PC and peripherals using a set of common signal lines, CPU bus and the various components through the exchange of data)