Managing Devices without Interrupts

Some devices don't generate interrupts with every significant state change. Even when the device does generate interrupts, a case can be made to drive an infrequently used, relatively slow device with a polled technique. Printer drivers are a common example of this technique. Since the printer device buffer is large in comparison to the physical print rate, a device driver has a considerable window in which it can occasionally check for the need to refill the buffer.

Working with Polled Devices

Once a device is started, it is generally unacceptable for driver code to hang in a tight loop waiting for the device to finish. In a multiprocessing and multitasking operating system such as Windows 2000, there are always useful chores that can or must occur in parallel with the device's operation.