Equipment are needed to adhere to a protocol so that the interrupt-ask for (IRQ) strains can be shared. The PCI bus features 4 interrupt traces, INTA# by INTD#, all of which are offered to every device. Nearly eight PCI units share the same IRQ line (INTINA# by means of INTINH#) https://nathanlabsadvisory.com/nist-800-cyber-security-frame-work/