Devices are required to follow a protocol so that the interrupt-ask for (IRQ) strains may be shared. The PCI bus incorporates four interrupt traces, INTA# by means of INTD#, all of which are available to every machine. Approximately 8 PCI units share the identical IRQ line (INTINA# through INTINH#) in https://nathanlabsadvisory.com/soc-2/