1.Maskable interrupt sources that cannot preempt the kernel code and are thus able to invoke operating system APIs from within their handlers.
不能抢占内核的掩码中断源，因此可以在处理程序中调用操作系统API。
2.Disabled. When the system is in this state both the maskable regular and fast interrupt sources are disabled.
当系统位于这个状态时，正规中断源于快速中断均禁止。
3.Init. When the system is in this state all the maskable interrupt sources are disabled.
当系统处于这个状态时所有的掩码中断源都是禁止的。
4.While transferring control to the proper segment, the processor clears the IF flag, thus disabling further maskable interrupts.
当将控制转移到合适的段时，处理器清除IF标志，因此关闭将来的可屏蔽中断。
5.When the IF flag of the flags register is clear, each maskable interrupt issued by the PIC is temporarily ignored by the CPU.
当eflags寄存器的IF标志为空时，PIC发出的每个可屏蔽中断都被CPU暂时地忽略。