.model small .stack 100h .data first db 13,10, 'Enter 1st Number: $' second db 13,10, 'Enter 2nd Number: $' result db 13,10, 'Result: $' invalid db 13,10, 'Invalid Number!!! $' .code start: mov ax,03 int 10h mov ax,@data mov ds,ax mn: mov dx, offset first mov ah,9 int 21h mov ah,1 int 21h mov cl,al cmp al,30h jl nvalid cmp al,39h jg nvalid jmp proceed nvalid: mov dx,offset invalid mov ah,9 int 21h jmp mn proceed: sub cl,30h mov dx,offset second mov ah,9 int 21h mov ah,1 int 21h cmp al,30h jl nvalid cmp al,39h jg nvalid sub al,30h xor ah,ah add al,cl aaa mov cx,ax add cx,3030h mov dx, offset result mov ah,9 int 21h mov ah,2 mov dl,ch int 21h mov dl,cl int 21h exit: mov ah,4ch int 21h end start