By Michael Cherry [bio]
Posted: Oct. 13, 2008

The following is an illustration accompanying an article published by Directions on Microsoft, an independent research firm focused exclusively on Microsoft strategy & technology. More samples of our content, as well as a list of upcoming articles and reports are also available.

MinWin is the smallest set of Windows OS components capable of running and providing fundamental OS services. It serves as a base on which a Windows development team can build reliable, secure, and well-performing client and server versions of Windows. In this illustration of Windows OS components, those believed to be included in MinWin are shown in gray.

Starting from the lowest level, the hypervisor is included because it is a small, highly tested and reliable OS kernel-like component that provides hardware virtualization.

Kernel-mode components (bottom) run in the privileged mode of the processor, which is restricted to highly tested and trusted code because all memory and CPU instructions are accessible in that mode. Major kernel-mode components include the Hardware Abstraction Layer, which provides the low-level interface to the computer hardware; the Windows Kernel, the low-level component responsible for OS services such as thread scheduling, interrupt handling, and exception dispatching; and the Windows Executive, which provides base services such as process, thread, and memory management, and the input/output subsystem. Some key device drivers, such as the network stack and a file system driver, also run in kernel mode in MinWin. Some complex and important systems that normally run in kernel mode, such as the windowing and graphics subsystem, are not included in MinWin because they differ based on the needs of the particular OS configuration.

At the user mode level (top), MinWin includes some key System Support Processes, such as the Session Manager, which starts Windows by starting the necessary subsystems, and the Service Control Manager, which is responsible for starting and managing Windows services. Some Service Processes, such as the DHCP network configuration service and client, are also included.