Units are required to comply with a protocol so which the interrupt-ask for (IRQ) lines is often shared. The PCI bus involves 4 interrupt strains, INTA# by way of INTD#, all of which are offered to every system. Up to eight PCI products share exactly the same IRQ line (INTINA# https://nathanlabsadvisory.com/iso-iec-19770-1-2017-it-asset-management/