Products are needed to follow a protocol so the interrupt-request (IRQ) traces is usually shared. The PCI bus features four interrupt strains, INTA# by INTD#, all of which can be found to each device. As many as 8 PCI devices share a similar IRQ line (INTINA# by means of INTINH#) https://nathanlabsadvisory.com/cis-center-internet-security/