But in hard drives where we actually have these moving platters, here is in fact, how we get from electricity and magnetism to those zeros and ones.

但是在传统硬盘中我们确实有高速运转的磁盘，这就是事实，但问题是我们如何,把电磁信号转化为0和1的。

哈佛公开课 - 计算机科学课程节选