title: How to subtract one from a memory location without using minus?
body: <p>I got this question on one of the interview question websites. The solution will be a code written in assembly language. I'm not very good in assembly and just wondering how it can be done. I know without minus we can subtract by adding (-1). That is taking 2's compliment. But exactly how should I write instruction is difficult for me. Any help will be appreciated.</p>
  
  <p>I got something like this:</p>
  
  <pre><code>MOV AX,b 
  Taking 2's compliment here 
  ADD AX,above mentioned command
  </code></pre>
  
  <p>I'm using X86.
  Thanks </p>