Another official Microsoft concept related to a tiny Windows core is . This is the absolute minimal kernel of the Windows operating system. In Windows 8, the MinWin core, which includes the NT kernel, memory manager, and file system drivers, is about 25 MB in total. The 161 files that comprise this core amount to roughly 20 MB . While impressive, MinWin is not a standalone operating system; it is the foundation upon which the full OS is built.