title: How do programs support i386 and ppc at the same time?
body: <p>I would like to know how you can support i386 and ppc architectures for programs at /bin.</p>
  
  <p>I run for instance</p>
  
  <pre><code>bin  $ file amber
  </code></pre>
  
  <p>I get</p>
  
  <pre><code>amber: setgid Mach-O universal binary with 2 architectures
  amber (for architecture i386):  Mach-O executable i386
  amber (for architecture ppc):   Mach-O executable ppc
  </code></pre>
  
  <p><strong>How do programs support i386 and ppc in the source code?</strong></p>
  
  <p>In other words, <strong>which components can you remove, for instance, in /bin/amber if you remove the support of ppc -architecture?</strong></p>