简要来说，启动引导程序是电脑开机后运行的第一个软件。

Briefly, a boot loader is the first software program that runs when a computer starts.

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GRUB启动引导程序仅搜寻特定的启动分区，找到后加载第二阶段的启动引导程序。

The GRUB MBR boot loader merely searches for a special boot partition and loads a second stage boot loader.

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不过对于JOS，我们将使用传统的硬盘驱动器启动机制，这意味着我们的启动引导程序必须符合那微不足道的512字节。

For JOS, however, we will use the conventional hard drive boot mechanism, which means that our boot loader must fit into a measly 512 bytes.

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