title: Tasm macros default value
body: <p>In turbo assembler i have a macro</p>
  
  <pre><code>subs macro x,y 
      mov ax,x
      sub ax,y
  endm
  </code></pre>
  
  <p>how can I give to y a default value, equal to 1, so I can write</p>
  
  <pre><code>subs bx
  </code></pre>
  
  <p>and ax becomes equal to bx - 1?</p>