title: 2's complement representation of fractions?
body: <p>I'm a little lost on this. I need to use two fractional bits 
  <code>0.(a-1)(a-2)</code></p>
  
  <p>Like that, now I can use <code>.00 .01 .10</code> and <code>.11</code>
  But I need negative numbers (in 2's complement) also, so would <code>.10</code> be <code>-.5</code> ? or would it be <code>-.25</code> ? 
  The same with <code>.11</code> , that would be <code>-.75</code>? or would it be <code>-.5</code> ? 
  I'm pretty sure it would be the former in both cases, but I'm not entirely positive.</p>