1、打开Keil uVision4，新建项目。
2、输入代码。
3、编译，0 error 0 waining.
4、效果，按下k1。led依次发光。
5、代码：#include <reg52.h>typedef unsigned char uchar;typedef unsigned int uint;sbit key=P3^2;//???? ????keyvoid delay(uint m){while(m--);}void main(){IT0=0; //???ж?0 ??0???????????1???????????EX0=1; //???ж?????λEA=1;P1=0xff;//led????1111 1111while(1); //?????????ɡ?}void Int0() interrupt 1{delay(1000); //???????if(key==0){P1=P1>>1; //?????λ}while(!key);//??????}