1．匯編源程序（中斷法）

SECOND EQU 30H

TCOUNT EQU 31H

ORG 00H

LJMP START

ORG 0BH

LJMP INT0X

START: MOV SECOND,#00H

MOV A,SECOND

MOV B,#10

DIV AB

MOV DPTR,#TABLE

MOVC A,@A+DPTR

MOV P0,A

MOV A,B

MOVC A,@A+DPTR

MOV P2,A

MOV TCOUNT,#00H

MOV TMOD,#01H

MOV TH0,#(65536-50000) / 256

MOV TL0,#(65536-50000) MOD 256

SETB TR0

SETB ET0

SETB EA

SJMP $

INT0X:

MOV TH0,#(65536-50000) / 256

MOV TL0,#(65536-50000) MOD 256

INC TCOUNT

MOV A,TCOUNT

CJNE A,#20,NEXT

MOV TCOUNT,#00H

INC SECOND

MOV A,SECOND

CJNE A,#60,NEX

MOV SECOND,#00H

NEX: MOV A,SECOND

MOV B,#10

DIV AB

MOV DPTR,#TABLE

MOVC A,@A+DPTR

MOV P0,A

MOV A,B

MOVC A,@A+DPTR

MOV P2,A

NEXT: RETI

TABLE: DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH

END

2．C語言源程序（中斷法）

#include AT89X51.H>

unsigned char code dispcode[]={0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71,0x00};

unsigned char second;

unsigned char tcount;

void main(void)

{

TMOD=0x01;

TH0=(65536-50000)/256;

TL0=(65536-50000)%6;

TR0=1;

ET0=1;

EA=1;

tcount=0;

second=0;

P0=dispcode[second/10];

P2=dispcode[second];

while(1);

}

void t0(void) interrupt 1 using 0

{

tcount++;

if(tcount==20)

{

tcount=0;

second++;

if(second==60)

{

second=0;

}

P0=dispcode[second/10];

P2=dispcode[second];

}

TH0=(65536-50000)/256;

TL0=(65536-50000)%6;

}