This viewer is compatible with both 32-bit and 64-bit operating systems (Windows® Vista® and Windows® 7). 

Note: This viewer is compatible with Trimble® PipeDesigner 3D®, Release 2013 v2, and can be used only on computers running AutoCAD® 2013, AutoCAD® Architecture 2013 and AutoCAD® MEP 2013. It will not work with previous versions of Autodesk applications or Trimble® PipeDesigner 3D®. Please make sure you download the viewer for a compatible version of AutoCAD.