IBM PC可以支持8级硬中断,时钟中断和键盘中断分别占据了其中的0级和1级。这两种中断处理程序都固化在ROM BIOS中,分别占据8088系统中断类型8和中断类型9(INT8和INT9)。程序设计工作者一般通过另外两个软中断INT 1AH和INT 16H来获得时钟和键盘信息。但是,在有些实际应用场合,需要通过修改和扩展INT8和INT9程序来实现某些特殊的功能。以键盘为例,通常必须在机器运行的程序中主动地读取键盘信 IBM PC can support 8 hard interrupts, clock interrupts and keyboard interrupts occupy one of 0 and 1 respectively. Both interrupt handlers are fixed in the ROM BIOS and occupy 8088 system interrupt type 8 and interrupt type 9 (INT8 and INT9), respectively. Programmers usually use two other soft interrupt INT 1AH and INT 16H to obtain the clock and keyboard information. However, in some practical applications, some special functions need to be implemented by modifying and expanding INT8 and INT9 programs. In the case of a keyboard, it is usually necessary to actively read a keyboard letter in the machine’s running program