ijlk

.DATA
    MSGA DB 13,10,"Input first number: ","$"
    MSGB DB 13,10,"Input second number:","$"
    MSGC DB 13,10,"The sum is: ","$"

    NUM1 db ?
    NUM2 db ?
    NUM3 db ?
.CODE
    MAIN PROC NEAR
        MOV AX, @DATA
        MOV DS, AX

        ; get first number
        LEA DX, MSGA
        MOV AH, 09h
        INT 21h

        MOV AH, 01
        INT 21H
        SUB AL, '0'

        MOV BL, AL

        MOV AH, 01
        INT 21H
        SUB AL, '0'

        MOV CL, AL

        ; get second number
        LEA DX, MSGB
        MOV AH, 09h
        INT 21h

        MOV AH, 01
        INT 21H
        SUB AL, '0'

        MOV DL, AL

        MOV AH, 01
        INT 21H
        SUB AL, '0'

        MOV DH, AL

        ; add
        MOV AL, CL
        MOV AH, BL
        ADD AL, DH
        AAA
        ADD AH, DL

        MOV NUM1, AL
        ADD NUM1, '0'

        ; if tens digit is less than or equal to 9
        CMP AH, 9
        JLE NOT_3DIGIT

        IS_3DIGIT:
        MOV AL, AH   ; move value of ah to al
        SUB AH, AH   ; clear ah
        ADD AL, 0    ; al + 0 = al (tens digit)
        AAA          ; move for addition
        ADD AH, 0    ; ah + 0 + 1 = ah + 1 (hundreds digit)
        MOV NUM2, AL
        MOV NUM3, AH
        ADD NUM2, '0'
        ADD NUM3, '0'
        ; output sum
        LEA DX, MSGC
        MOV AH, 09h
        INT 21h
        MOV DL, NUM3
        MOV AH, 02H
        INT 21h
        MOV DL, NUM2
        MOV AH, 02H
        INT 21h
        JMP PRINT_LASTDIGIT


        NOT_3DIGIT:
        MOV NUM2, AH
        ADD NUM2, '0'
        ; output sum
        LEA DX, MSGC
        MOV AH, 09h
        INT 21h
        MOV DL, NUM2
        MOV AH, 02H
        INT 21h

        PRINT_LASTDIGIT:
        MOV DL, NUM1
        MOV AH, 02H
        INT 21h

        EXIT:
        MOV AH, 4Ch
        INT 21h

    MAIN ENDP
END MAIN