8086实现8259的中断控制器，非常方便-8086 to achieve the 8259 interrupt controller, a very convenient

开源CPU软核8086的源码,波兰版Verilog源码-8086 soft-core CPU revenue source, the Polish version of Verilog source code

实现中断服务的程序,PC机用户可使用的硬件中断只有可屏蔽中断，由8259中断控制器管理。中断控制器用于接收外部的中断请求信号，经过优先级判别等处理后向CPU发出可屏蔽中断请求,灯亮来表明中断实现.-Interrupt service program to achieve, PC machine users can use hardware interrupts may be maskable interrupt only by the 8259 interrupt controller mana

the USB function of the 82c693 has it s interrupt connected to the 2nd 8259 controller. So we have to check for it first.

8259 interrupt controller emulation.