When C and UNIX were developed in the early1970s, the concept of exceptions, which interrupt the flow of an application when some condition occurs, was fairly new or non-existent. 世纪70年代早期开发C和UNIX时,在发生某一条件时中断应用程序流的异常还是相当新或尚不存在的概念。
DR7 is used to further define the breakpoint interrupt condition. DR7用来进一步定义断点的中断条件。