装配中断问题:int 13h (ah = 42h)失败返回cf = 1, ah = 1。

I want to write a program in assembly language to read primary partitions of a hard disk. I Googled a lot last several days and I found that maybe int 13h (ah = 42h) is for me. But I failed at the beginning. After INT 13H was called, CF was set to 1 and AH was 1. From the docs I know the interrupt was failed.I want to write a program in assembly language