Microsoft KB Archive/103883
Article ID: 103883
Article Last Modified on 7/30/2001
This article was previously published under Q103883
LOCAL I/O OPERATION
When an application requests I/O services, the underlying operating system calls device driver software that is resident in BIOS on most MS-DOS PCs. Device driver software is written to communicate with the device controller card, and can thus forward the I/O request to firmware that is resident on the controller.
The device controller then provides the required control signals to the device.