This is no answer, just your program enclosed into <pre> and </pre> tags:

#include
char Pencacah20;
char Secon;
char Minute;
char Hour;

char Segmen[6];//
sbit at 0xA0 Hour_Button      ;
sbit at 0xA1 TombolMinute    ;
sbit at 0xA2 Secon_Button		;
sbit at 0xA3 INC_Hour_Button;
sbit at 0xA4 INC_Minute_Button;
sbit at 0xA5 INC_Secon_Button;

//****** array number 0-9 *******
void Segmen2Digit (unsigned char c, unsigned char pos){
code char Segmen_Com[]={0x01,0xC7,0x22,0x82,0xC4,0x88,0x08,0xC3,0x00,0x80};
	Segmen[pos++] = Segmen_Com[c/10];
	Segmen[pos]	  =Segmen_Com[c%10];
	}
	
void Change_View   (void){
	Segmen2Digit(Hour,0);
	Segmen2Digit(Minute,2);
	Segmen2Digit(Secon,4);//
	}
	
//******Delay time 1 digit number*******
void WaitMomen() {//wait 1m secon

TH1=(-1500/256)-1;
TL1=(-1500%256);
TF1=0;			//Timer Flag 1 =0
TR1=1;		
while (!TF1);	
}
//****Main program******************************************

void main (void) {
	Pencacah20=20;		
	Hour=Minute=Secon=0;	
	Change_View();
	
	TH0=(-50000/256)-1;
	TL0=(-50000%256);
	
	TMOD=0x11;			
	ET0=1;			
	EA=1;			
	TR0=1;			
	
	while(1)		
	{
	P1=Segmen[0];		
	P0=0xDF;			
	WaitMomen();
	P1=Segmen[1];		
	P0=0xEF;			
	WaitMomen();
	P1=Segmen[2];			
	P0=0xF7;			
	WaitMomen();
	P1=Segmen[3];			
	P0=0xFB;			
	WaitMomen();
	P1=Segmen[4];			
	P0=0xFD;			
	WaitMomen();
	P1=Segmen[5];			
	P0=0xFE;			
	WaitMomen();
	}
	}
	//1111 1111
		//**********change Hour digit*************
	
void ChangeHour (void){
	Hour +=1;			
	if (Hour==24){  Hour = 0 ;			
	Change_View();
	}
}
	
	
void ChangeMinute(void){
	Minute +=1;			
	if (Minute==60){		
	Minute = 0 ;			
	ChangeHour();	}		
	Change_View();
	}
	
	
	void ChangeSecon(void)	{
	Secon +=1;		
	if (Secon==60)	{		
	Secon=0;		
	ChangeMinute();	}
	Change_View();
}



void Increment_Hour(void) {
Hour -=1;
if(Hour==0) {
Hour=24;
Change_View();
}
}

void Increment_Minute(void){
	Minute -=1;			
	if (Minute==0){		
	Minute =59 ;			
	Increment_Hour();	}		
	Change_View();
	}
	
	void Increment_Secon(void)	{
	Secon -=1;		
	if (Secon==0)	{		
	Secon=0;		
	Increment_Minute();	}
	Change_View();
}
	


void Check_Button (void)	{
	if (!Hour_Button)	ChangeHour();		
	else
		if (!TombolMinute)	ChangeMinute();
		else 
		if(!Secon_Button)		ChangeSecon();
		else
		if(!INC_Hour_Button)   Increment_Hour();
		else
		if(!INC_Minute_Button)    Increment_Minute();
		}
		
		
		void TimerInterrupst(void)		interrupt 1 using 1	{
		
		
		TH0=(-45000/256) -1;            
		TL0=(-45000%256);
		
		Pencacah20 -=1;		
		if (!Pencacah20)		{	
		Pencacah20=20;			
		Check_Button();
		ChangeSecon();		}
		}

See also http://www.8052.com/faqs.phtml?FAQ=120199 and the

JW