Devices are necessary to comply with a protocol so the interrupt-ask for (IRQ) traces could be shared. The PCI bus features 4 interrupt strains, INTA# as a result of INTD#, all of which are offered to every product. As many as 8 PCI units share a similar IRQ line (INTINA# https://nathanlabsadvisory.com/ciso-services-virtual-ciso/