Devices Are necessary to stick to a protocol so the interrupt-ask for (IRQ) lines could be shared. The PCI bus incorporates 4 interrupt lines, INTA# by means of INTD#, all of which are offered to each gadget. As much as eight PCI units share precisely the same IRQ line (INTINA# https://nathanlabsadvisory.com/iso-20000-1-it-services/