ORG????? 00H?????????????? ；指定下條指令的地址

AJMP???? MAIN????????????? ；跳轉至MAIN

50M

??????? INC????? 23H

??????? RETI

??????? ORG????? 001BH????????????? ；定時器T1中斷入口，T1作定時，T0作計數

??????? PUSH???? A????????????????? ；累加器A壓入堆棧

?????? ?PUSH???? PSW??????????????? ；狀態寄存器壓入堆棧

??????? DJNZ???? 40H，JJ??????????? ；產生1s定時時標

??????? MOV????? 40H，#0C8H

??????? DJNZ???? 41H，JJ

??????? CLR????? P3.1?????????????? ；關閉閘門

??????? ANL????? 88H，#0AFH???????? ；1s末，關閉T0和T1

??????? MOV????? 20H，P1

????? ??MOV????? 21H，TL0?????????? ；T0計數值送21H和22H

? MOV????? 22H，TH0

? SETB???? P3.0?????????????? ；LS393清零

? ACALL??? COUNT??????????? ；調用二進制轉BCD碼程序

JJ：??? POP????? PSW

??????? POP????? A

??????? RETI

??????? ORG????? 50H??????????????? ；以下程序從地址50H開始

MAIN：? MOV????? SP，#50H?????????? ；將初始值賦予SP

MOV????? TH1，#06H????????? ；將初始值賦予TH0