问我做了一个计算的循环，现在我想在汇编中对结果求和。

EN

.model small
.stack 100h
.data

 num1 db
 num2 db 9
 result db ?
 sum db

 msg1 db 10, 13,"Enter a number: $", 10, 13
 msg2 db 10, 13,"Difference is: $",10, 13
 msg3 db 10, 13,"Sum is: $",10, 13

 .code
     main proc

     mov ax, @data
        mov ds, ax

        mov cx,5

        process:

        mov dx, offset msg1
        mov ah,9 ; used to print the string/msg with
        int 21h ;this



        mov ah, 1 ;READ a Character from Console,
                  ;Echo it on screen and save the
                  ;value entered in AL register
        int 21h

        sub al, 30h ;keep the value enter in bcd form
        mov num1, al ;move num1 to al
        ;al is used for input


        ;sub al, 30h
        mov al, num2 ;move num2 to al

        sub al, num1 ;

        mov result, al ;move whats in al to result


        mov bl,al
        add sum,bl
        ;add al,sum

        mov ah,0 ;clears whats in ah
        aaa ;used to convert the result to bcd
        ;and first digit is stored in ah
        ;second digit stored in al


        add ah, 30h ;convert whats in ah to ascii by adding 30h
        add al, 30h ;convert whats in al to ascii by adding 30h
        mov bx, ax ;saving whats in ah and al in bx register



        mov dx, offset msg2
        mov ah,9 ; used to print the string/msg  
        int 21h



        ;the following is used to print whats in the bh register
        ;dl is used for output
        ;2 or 2h means to write/print whats in dl
        ;so the value to be printed is moved to dl
        mov ah,2
        mov dl, bh
        int 21h


        ;the following is used to print whats in bl
        mov ah,2
        mov dl, bl
        int 21h

        loop process

        mov dx, offset msg3
        mov ah,9 ; used to print the string/msg  
        int 21h

        mov ah,2
        mov dl, bh
        int 21h


        ;the following is used to print whats in bl
        mov ah,2
        mov dl, bl
        int 21h

     mov ah, 4ch ;4ch means to return to OS i.e. the end
     ;of program
     int 21h
    main endp ;ends the code
end main ;ends main