定义situation dw 0000_0011_0000_1100b（表示南北移动），s2 dw 0000_0110_1001_1010b（南北到东西的过渡），s3 dw 0000_1000_0110_0001b（东西移动）s4 dw 0000_0100_1101_0011b（东西到南北的过渡）。将situation的偏移地址给SI，将其从4号端口输出，让situation状态保持5秒，SI+2转到下一个状态。（基本要求流程图如图2.1）-With the definition it later. Dw 0000_0011_0000_1100b (said north-south movement), s2 dw 0000_0110_1001_1010b (north and south to the things of the transition) the s3 s4 the dw 0000_1000_0110_0001b (something moving) dw 0000_0100_1101_0011b (something to the north and south of the transition). Offset address of the situation to the SI, the output port from the 4th and hold for five seconds, so that the situation state the, SI+2 go to the next state. (The basic requirements of the flow chart in Figure 2.1)