Equipment are required to abide by a protocol so that the interrupt-request (IRQ) strains could be shared. The PCI bus features four interrupt lines, INTA# by INTD#, all of which are offered to each product. Approximately 8 PCI devices share a similar IRQ line (INTINA# by means of INTINH#) in https://nathanlabsadvisory.com/iso-20000-1-it-services/