```c
#include <reg51.h>
#include <stdio.h>
//unsigned char a=0;
void delay()
{
unsigned int i;
unsigned int j;
for(i=0;i<500;i++)
for(j=0;j<20;j++);
}
void light() interrupt 1
{
unsigned int i;
for(i=0;i<5;i++)
{
P1=0xf0;
delay();
P1=0x0f;
delay();
}
P1=0xff;
}
void main(void)
{
P1=0xff;
IT1=1;
IE=0x84;
while (1)
;
}
把a的注释去了中断就不执行了