Input/Output Services:  

Every operating system, large or small, provides input/output services for each device in the system. The operating system includes I/O device driver programs for each device installed on the system. These drivers provide services to the file management system and are also available, through the API, to other programs for their use. The I/O device drivers accept I/O requests and perform the actual data transfers between the hardware and specified areas of memory.  

Devices drivers for newly installed devices are added and integrated into the operating systems. In Windows, this capability is known as plug-and-play.