Interrupt Removal Background

On modern operating systems, hardware interrupts are typically serviced in a high-priority execution context that runs as part of the OS kernel. When a hardware interrupt occurs, the OS kernel will execute its chain of interrupt service routines until a single ISR "claims" the interrupt by telling the OS kernel that its device is currently interrupting. Once the interrupt is claimed, the individual ISR must acknowledge the pending interrupt before returning control to the operating system. When the interrupt is no longer pending, the OS will return control to the user application (for example, your instrument driver). By specifying the steps necessary to acknowledge a pending interrupt for your device, you are telling NI-VISA how to service interrupts for your device inside the OS kernel.