When you're working on a file, it's saving constantly to RAM but also hopefully to disc, the hard disk so you don't actually lose it if the power goes off.

当你打开一个文件，它不断地保存在内存中,但对于光盘，硬盘,当你断开电源的时候，数据不会丢失。

哈佛公开课 - 计算机科学课程节选

This is different from the hard disk, which is where files and stuff are permanently stored.

这个和硬盘是不一样的，那是存储,文件之类的东西的。

哈佛公开课 - 计算机科学课程节选

Good question, so what happens when you format a floppy disk or format a hard drive?

好问题，当你格式化一个软盘,或者硬盘时会发生什么呢？

哈佛公开课 - 计算机科学课程节选