DATA SEGMENT
HOUR DB ?
MIN  DB ?
SEC  DB ?
TS   DB 0AH,0DH,'PLEASE INPUT THE CURRENT TIME: $'
TS1   DB ':$'
DATA ENDS 

CODE SEGMENT
     ASSUME CS:CODE,DS:DATA
;-----------輸入分鐘和秒函數-----------
INPUT PROC
       MOV AH,1
       INT 21H
       SUB AL,30H 
       CMP AL,6
       JGE EXIT1
       MUL CL
       MOV DL,AL
       MOV AH,1
       INT 21H
       SUB AL,30H
       ADD AL,DL      
EXIT1: RET
INPUT  ENDP
;-----------輸入小時函數-----------
INPUT2 PROC
       MOV AH,1
       INT 21H
       SUB AL,30H
       CMP AL,2
       JG EXIT2
       MUL CL
       MOV DL,AL
       MOV AH,1
       INT 21H
       SUB AL,30H
       CMP AL,4
       JG EXIT2
       ADD AL,DL
EXIT2: RET
INPUT2 ENDP
;----------輸出時間函數--------------
OUTPUT PROC
       PUSH DX
       PUSH SI
       MOV DL,30H
   L1: CMP SI,10
       JB  L2
       INC DL
       SUB SI,10
       JMP L1
   L2: MOV AH,2
       INT 21H
       MOV DX,SI
       ADD DL,30H
       MOV AH,2
       INT 21H
       POP SI
       POP DX
       RET
OUTPUT ENDP 
;-----------清屏函數---------------------
CLS    PROC
       PUSH AX
       PUSH BX
       PUSH CX
       PUSH DX
       MOV AX,0600H  ;AH=06(滾動)，AL=00(全屏空白)
       MOV CX,0      ;左上角行：列
       MOV DX,184FH  ;右下角行:列
       MOV BH,7
       INT 10H
       POP DX
       POP CX
       POP BX
       POP AX
       RET
CLS  ENDP
;---------------光標位置設置函數----------
 POS   PROC 
       PUSH BX
       PUSH DX
       PUSH AX
       MOV BH,0
       MOV DX,0048H
       MOV AH,2
       INT 10H
       POP AX
       POP DX
       POP BX
       RET
POS   ENDP 
;------------主函數---------------------------
MAIN PROC FAR
START: PUSH DS
       XOR AX,AX
       PUSH AX
       MOV AX,DATA
       MOV DS,AX
       LEA DX,TS
       MOV AH,9
       INT 21H
       MOV CL,10
;--------------輸入小時------
       CALL INPUT2
       MOV HOUR,AL
       LEA DX,TS1
       MOV AH,9
       INT 21H
;--------------輸入分鐘------
       CALL INPUT
       MOV MIN,AL
       LEA DX,TS1
       MOV AH,9
       INT 21H
;-------------輸入秒-------
       CALL INPUT
       MOV SEC,AL
       
       
WAIT2: MOV AH,1
       INT 16H
       CMP AL,0DH
       JZ EXIT            ;檢查有無輸入回車（停止標志）
       MOV BX,20000
WAIT1: MOV CX,11204
 DELY: LOOP DELY           ;延遲一秒鐘
       DEC BX
       JNZ WAIT1
       CALL CLS

       INC SEC
       CMP SEC,60          ;秒加一
       JNZ  AD
       INC MIN             ;分鐘加一
       MOV SEC,0H
       CMP MIN,60
       JNZ AD
       INC HOUR            ;小時加一
       MOV MIN,0H
       CMP HOUR,24
       JNZ AD
       MOV HOUR,0H
       
       
;-----------------------
   AD: CALL POS           ;調用清屏函數
     
;----------------------
       MOV AL,HOUR
       CBW
       MOV SI,AX
       CALL OUTPUT        ;輸出小時
       
;------------------------
       LEA DX,TS1
       MOV AH,9
       INT 21H
;----------------------
       MOV AL,MIN
       CBW
       MOV SI,AX
       CALL OUTPUT         ;輸出分鐘
       
;------------------------
       LEA DX,TS1
       MOV AH,9
       INT 21H
;----------------------
       
       MOV AL,SEC
       CBW
       MOV SI,AX
       CALL OUTPUT         ;輸出秒鐘
       JMP WAIT2


EXIT:  RET
MAIN   ENDP
CODE   ENDS
       END START