Products are required to observe a protocol so which the interrupt-ask for (IRQ) strains is usually shared. The PCI bus contains 4 interrupt strains, INTA# through INTD#, all of which are offered to each gadget. Nearly eight PCI products share the identical IRQ line (INTINA# through INTINH#) in APIC-enabled x86 https://nathanlabsadvisory.com/irs-efile/