//ex3_.c
#include <reg51.h>
void delay(unsigned char i);
void main()
{
     while(1){
       P1=0*00
       delay(200);
       p1=0*ff
       delay(200);
         }
}
void delay(unsigned char i);
{
unsigned char i,k;
for(k=0;k<1;k++)
for(j=0;j<225;j++);
}

对啊。。。我照着书抄的啊