扩展int13h调用详解(修正)

(因此最多可以有四个主分区).
    Boot Record ID 即引导区标记占用两个字节 (0x1FE and 0x1FF), 对于合法引导区, 它等于 0xAA55, 这是判别引导区是否合法的标志.
    Boot Sector 的具体结构如下图所示 (参见 NightOwl 大侠的文章):

      0000  |------------------------------------------------|
            |                                                |
            |                                                |
            |             Master Boot Record                 |
            |                                                |
            |                                                |
            |             主引导记录(446字节)                |
            |                                                |
            |                                                |
            |                                                |