Devices are needed to abide by a protocol so the interrupt-request (IRQ) strains could be shared. The PCI bus incorporates 4 interrupt lines, INTA# through INTD#, all of which are available to every product. Nearly 8 PCI gadgets share the same IRQ line (INTINA# by way of INTINH#) in APIC-enabled https://nathanlabsadvisory.com/adgm-data-protection-regulation-compliance/