4位数码管计数单片机

#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int  
sbit P20=P2^3; //第三个数码管//
sbit P21=P2^2; //第二个
sbit P22=P2^0; //第一个
unsigned char code dis[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x40};
uint disnum;
uchar count;
void delay();
void display(uchar ,uchar ,uchar );

void main()
{
TMOD=0x01;
TR0=1;
ET0=1;
EA=1;
TH0=0Xd8;
TL0=0Xf0;
P2=0x00;
while(1)
{
if(count==100)
{
count=0;
disnum++;
  if(disnum==1000)
   {disnum=0;
   }