Now this is a rain gauge, and it's sitting on a roof of a building, and when the water falls into this gauge, it sends a signal to the logic unit of the computer, which immediately notifies the memory bank of the computer to seek out its instructions for a rainy day.

这是一个雨量测量器，安装在一个楼房的,屋顶上，当水流入到这个测量器，它就给计算机的逻辑部件发送一个信号，计算机立即通知内存条,为下雨天找出相应的指令。

计算机科学课程节选 : 哈佛公开课