Data Center | 2. April 2008 | Helge Klein Windows x64 – All the Same Yet Very Different, Part 6: COM, DLLs and ProcessesThis is the sixth part of a mini-series on Windows x64, focusing on behind the scene changes in the operating system. In the last article I discussed how 32-bit applications are wrapped up in the WoW64 subsystem. Today we will take a deeper look at some limitations of 64-bit Windows and what they mean in practice. RulesApplication interoperability and execution on Windows x64 is governed by a few simple rules, most of which you already know:The kernel cannot execute 32-bit code.