说明：  编程将8253计数器0，计数器1的工作方式设定为方式2，用作分频器，定时器2工作在方式3，方波；定时器0的输出作为定时器1的输入，定时器1的输出作为定时器2的输入，定时器2的输出接在LED上，运行后可观察到该LED灯在不停的闪烁。
(Programming will be 8253 counter 0, counter 1 work set to Mode 2 for the prescaler, the timer 2 in the way of 3, square Timer 0 Timer 1 output as the input, timer 1 Timer 2 output as the input, timer 2, then the LED output, the run can be observed that the LED lights flicker in the non-stop.)