Which files are different between the single and multiprocessor versions of Windows XP and later?

A. The core OSs are the same for both uniprocessor and multiprocessor systems. The only real differences are in the underlying Windows kernel (which is implemented along with the Executive subsystem in Ntoskrnl.exe) and the hardware abstraction layer (HAL--hal.dll). Windows versions earlier than Windows Server 2003 and XP did have some additional files that differed (Windows 2000 also had separate versions of Win32k.sys, NTdll.dll, and Kernel32.dll). When Windows is installed, it detects the processor requirements and copies the relevant file from the media to the standard name (e.g., ntoskrnl.exe) on the installed OS. The Table shows the files that differ between the uniprocessor and multiprocessor versions of XP. Note that the Ntkrnlpa.exe is used only on systems that have invoked the Physical Address Extension (PAE) kernel, which allows access to as much as 64GB of memory. Essentially the uniprocessor version of the kernel doesn't have the mutliprocessor synchronization algorithms, which are more complex and time-consuming, so they're a waste of processing resources for systems with only one processor.