在设计硬件电路时，要充分利用实验仪上的接口芯片，如8051单片机、8255并行接口芯片、发光二极管（红、黄、绿各两个）。 设计或利用接口仪上已有的单脉冲发生器，但脉冲发生器产生的负脉冲来产生中断，进行模拟有急救车通过。-In the design of hardware circuit, we should make full use of the experimental apparatus of the interface chip, such as the 8051, 8255 parallel interface chip, light-emitting diodes (red, yellow and green of the two). Miriam interface design or use of the existing single-pulse generator, but the pulse generator to generate negative pulse interruption, to simulate an ambulance through there.