Equipment are required to adhere to a protocol so that the interrupt-ask for (IRQ) lines can be shared. The PCI bus contains four interrupt traces, INTA# through INTD#, all of which are offered to each device. As many as eight PCI devices share precisely the same IRQ line (INTINA# as https://nathanlabsadvisory.com/achieve-pci-dss-compliance-in-the-usa-secure-your-business-today/