diff -r 70d0c3102424 -r 411b72b73d8f Hardware/HDD/HDD.cs
--- a/Hardware/HDD/HDD.cs	Thu May 06 19:20:38 2010 +0000
+++ b/Hardware/HDD/HDD.cs	Sun May 09 16:22:13 2010 +0000
@@ -110,6 +110,12 @@
     #pragma warning disable 67
     public event SensorEventHandler SensorAdded;
     public event SensorEventHandler SensorRemoved;
-    #pragma warning restore 67
+    #pragma warning restore 67    
+
+    public void Accept(IVisitor visitor) {
+      visitor.VisitHardware(this);
+    }
+
+    public void Traverse(IVisitor visitor) { }
   }
 }