#include#includevoid delay(int a){unsigned char i;while(a--)for(i=0;i<120;i++);}void ext0() interrupt 0{P1=0xff;delay(5000);}main(){unsigned char led=0xfe;EX0=1;IT0=1;EA=1;while(1) { P1=led; led=_crol_(led,1); delay(500); }}