take 2 digit input , decresing order print to zero

.MODEL SMALL
.STACK 100H
.DATA

.CODE
MAIN PROC

;INITIALIZE DS
MOV AX,@DATA     ; not sure this is really needed in model .small
MOV DS,AX

MOV AH,1         ;SCAN MSB
INT 21H          ;MSB IS NOW AT AH
MOV BH,AL        ;SAVE IT TO BH

                 ;SCAN LSB
MOV AH,1         ;LSB IS NOW AT AL
INT 21H          ;SAVE IT TO BL
MOV BL,AL

MOV AH,2         ;SINGLE CHAR PRINT
MOV DL,0DH       ;CARRIAGE RETURN
INT 21H          ;AL = 0DH
MOV DL,0AH       ;LINE FEED
INT 21H          ;AL = 0AH

LOOP1:
    MOV DL,' '     ;SPACE
    INT 21H
    MOV DL,BH      ;MSB
    INT 21H
    MOV DL,BL      ;LSB
    INT 21H

    DEC BL         ;DECREMENT LSB
    CMP BL,'0'-1   ;LET 70
                   ;SO UPDATE O TO 9
                   ;AND 7 TO 6
    JNE LOOP1      ;IF FALSE

UPDATE_IT:         ; IF LST was zero

    MOV BL,'9'     ;TURN LSB O TO 9
                   ;EXAMPLE 80 TO 79

    DEC BH
    CMP BH,'0'-1   ;BOTH MSB
                   ;AND LSB ARE ZERO
    JNE LOOP1

;DOS EXIT
EXIT_:
MOV AH,4CH         ;DOS EXIT FUNCTION
INT 21H            ;EXECUTE

MAIN ENDP
END MAIN