Units are required to adhere to a protocol so the interrupt-ask for (IRQ) lines might be shared. The PCI bus contains 4 interrupt strains, INTA# by way of INTD#, all of which can be found to each unit. As much as eight PCI equipment share the same IRQ line (INTINA# https://nathanlabsadvisory.com/cism-certified-information-security-manager/