When I try to DIV I get "Divide by zero" But its not zero

Question

When I try to divide a number by two I get "Divide by zero" error.

Current status:

AX = 0009

I have this line

Two DW 2

And when I am trying to do

DIV Two

I get this error:

What is the problem?

Answer 1

You need to clear dx before dividing. Recall, div divides DX:AX by the operand, not just DX. If you do not clear DX, the resulting quotient does not fit into a 16 bit word, causing the CPU to generate an exception. This is the same exception you get for a division by zero and the debugger doesn't try to tell the two error sources apart.