Products Are needed to abide by a protocol so that the interrupt-request (IRQ) lines may be shared. The PCI bus features four interrupt strains, INTA# through INTD#, all of which can be found to each machine. Up to eight PCI units share exactly the same IRQ line (INTINA# via INTINH#) https://nathanlabsadvisory.com/copyright-currency-security-standard/