Hardware Devices Communicating with the Computer

After the computer has loaded the operating system, hardware attached to the computer must be able to communicate with the CPU. Hardware communication is done by using an interrupt request (IRQ). Each time hardware needs the attention of the computer the interrupt controller sends the request (INTR) to the CPU to stop what it is doing to process the request. Anything that was being currently done by the CPU is put on hold and stored as a memory address in the memory stack and is returned to after the interrupt request is processed.