Pretty input 2 numbers and output result of summ this number

data    segment
        a dw ?
        nmb db ?
        answer db 0h

        result db 0h

        ax_temp dw ?
        bx_temp dw ?
data    ends

code    segment
        assume cs:code, ds:data
main:   mov dx, data
        mov ds, dx

        mov dx, 0B800h ; Base of videomemory;
        mov es, dx
        xor di, di
        xor dx, dx ; Clear display;
        mov ax, 0720h
        mov cx, 80*25
        rep stosw
        jmp gen

outp_n:
        add di, 2
        mov ax, 0730h
        add al, nmb
        mov es:[di], ax
ret

start:  mov cx, 02h
inloop: in  al, 60h
        cmp al, bl
        je  inloop
        mov bl, al
        cmp al, 01h
        jne NotEsc
        jmp quit
NotEsc: cmp al, 0Bh
        jne CkInNum
        mov a, 0
        mov es:[di], 0730h
        jmp NxtNum
CkInNum:cmp al, 02h ; check scancode in range;
        jl Not9
        cmp al, 0Ah
        jg Not9
        mov ah, 0h
        mov si, ax
        dec si
        mov a, si
        add si, 0730h
        mov es:[di], si
        jmp NxtNum
Not9:   jmp inloop
NxtNum:
        mov ax_temp, ax ; Answer;
        mov bx_temp, bx
        mov bl, 0Ah
        mov al, answer
        mul bl
        add ax, a
        mov answer, al
        mov ax, ax_temp
        mov bx, bx_temp

        inc di
        inc di
        dec cx

        jnz Not9
        mov ax, 0h
ret

gen:
        mov di, 0 ; Input 2 numbers;
        call start
        mov es:[di], 072Bh ; 2B - ascii +;
        mov al, result
        add al, answer
        mov result, al
        mov answer, 0h
        add di, 2
        call start
        mov es:[di], 073Dh ; 3D - ascii =;
        mov al, result
        add al, answer

        mov bl, 0Ah
        div bl ; Get div of number;

        mov nmb, al ; Number output;
        mov bl, ah
        call outp_n
        mov nmb, bl
        call outp_n

pause:  in al, 60h
        cmp al, 01h
        jne pause
quit:   mov ax, 4C00h
        int  21h
code    ends
        end main