The IOS is a required system virtual device that carries out all control and management tasks for Windows 95 protected-mode drivers. The primary responsibilities of the IOS are to load and initialize protected-mode device drivers and to provide the services clients and device drivers need to make and complete requested I/O operations.
This part of the Windows 95 DDK Design and Implementation Guide describes the input and output supervisor (IOS), describes the IOS services that control and manage protected-mode device drivers and that permit IOS clients, such as file system drivers, to generate I/O requests to be passed to the device drivers.