Products are necessary to adhere to a protocol so which the interrupt-request (IRQ) lines can be shared. The PCI bus includes 4 interrupt traces, INTA# via INTD#, all of which are offered to every unit. Around 8 PCI equipment share precisely the same IRQ line (INTINA# by means of INTINH#) https://nathanlabsadvisory.com/eu-gdpr/