当您学习如何配置计算机的启动设置时，您可能会对BIOS和CMOS感到困惑。您实际访问哪一个来更改这些设置？今天的超级用户问答帖子回答了一位好奇的读者的问题。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

照片由gynti_46（Flickr）提供。

问题

超级用户reader Space Ghost想知道他是否在启动时访问BIOS或CMOS：

For the longest time I have assumed I was entering the BIOS setup and that CMOS is a chip that holds the BIOS settings I set/choose in its memory.

I recently read somewhere that when I am configuring boot order, etc. that it is actually the CMOS setup. I am a little bit confused now, could someone explain this to me?

启动期间，Space Ghost是否访问BIOS或CMOS？

答案

超级用户贡献者Frank Thomas为我们提供了答案：

Both. CMOS stores BIOS configuration information. When you enter setup, you are running the BIOS’s configuration program, which loads the settings defined in CMOS. You are “setting up” the CMOS by providing configuration information the BIOS will use as it runs.

The BIOS is a program written as firmware onto a ROM so that it cannot be written to (except by an all-or-nothing flash operation, which is dangerous, so not an everyday operation). The BIOS ROM stores its configuration information on the CMOS when you hit F10. That is why clearing the CMOS restores your BIOS settings to default and does not delete the BIOS itself, leaving you with an expensive paperweight.

For example, the BIOS has a subroutine that will load the operating system per the boot order. The boot order information, however, (i.e. use first CD-ROM as first device) is stored in the CMOS. If you clear the CMOS, the BIOS will use a default, usually the first disk on the first disk controller that is populated.

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