Equipment are needed to observe a protocol so the interrupt-ask for (IRQ) strains can be shared. The PCI bus involves four interrupt traces, INTA# via INTD#, all of which are available to every product. Approximately 8 PCI units share the identical IRQ line (INTINA# via INTINH#) in APIC-enabled x86 methods. https://nathanlabsadvisory.com/aramco-cyber-security-compliance/