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

And so this is why in problem set 5 last year when I took photographs on campus with a compact flash card, just standard consumer media and I accidentally formatted that compact flash card, I only lost the first few kilobytes, the first few thousand bits on that compact flash card.

这也是去年的套题5中,我们在校园里面用配有，简易闪存卡的标准摄像机拍照片,我不小心格式化了这个简易闪存卡,其实我只是丢失的最开头的几千个字节的数据。

哈佛公开课 - 计算机科学课程节选