MOV TMOD,#01H
MOV TH0,#(65536-50000) / 256 MOV TL0,#(65536-50000) MOD 256 SETB TR0
DISP: 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
WAIT: JNB TF0,WAIT CLR TF0
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: LJMP DISP NEXT: LJMP WAIT
TABLE: DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH END
7． C语言源程序（查询法） #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)%256;