随着计算机硬件的进步和改进，为什么像CMOS电池这样的东西仍然是必要的呢？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。

照片由吉姆·鲍尔（Flickr）提供。

问题

超级用户读者Joseph Philipson想知道为什么PC仍然需要CMOS电池：

Why do PCs still require a CMOS battery even though they run on electricity? We are providing lots of power to the PC by switching the CPU plug to our electric board, so why does it still require a CMOS battery?

为什么个人电脑还需要CMOS电池？

答案

超级用户贡献者nhinkle和**okes2345为我们提供了答案。首先，nhinkle：

The CMOS battery is not there to provide power to the computer when it is in operation, it is there to maintain a **all amount of power to the CMOS when the computer is powered off and unplugged.

The primary function of this is to keep the clock running even when the computer is turned off. Without the CMOS battery, you would need to reset the clock every time you turned on the computer.

On older systems the CMOS battery also provided the **all amount of charge required to maintain the non-volatile BIOS memory, which remembered BIOS settings between reboots. On modern systems this information is typically stored in flash memory and does not require a charge to be maintained.

接下来是**okes2345的答案：

Think of it like your car battery. When you unplug the battery, your radio looses all of its presets and the clock resets. Originally, the CMOS battery held a similar function, maintaining the memory that held the BIOS settings and keeping the Real-Time Clock running.

However, with modern computers the CMOS battery plays a lesser role as most BIOS firmware is **art enough to automatically detect the correct settings and those settings are stored such that they do not need power to persist. The CMOS battery is still required to maintain the RTC though.

More information is available at the following Wikipedia page: Nonvolatile BIOS Memory (CMOS Battery)

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