divide emu 8086 assembly error [duplicate]

Question

Possible Duplicate:
ASM x86 integer overflow

I get a divide error- overflow and am not sure why. Here is the complete code that reproduces the error

include emu8086.inc

org 100h

       mov ax, 2 
       mov bx, 10
       div bx

       mov ax, 2
       mov bx, 2
       div bx   
       ret

Answer 1

Try adding xor dx, dx before each div and see if that doesn't help.

Since you're specifying a 16-bit target, div divides dx:ax by that target. If dx starts out containing a large number (more accurately, anything but quite a small number), the result will overflow. Even if it doesn't overflow, your result won't just be ax/bx as you apparently intend.