Abstract: A support facility for installation of interprocessor unit cabling interconnecting the processor units of a multiple processor unit system in a first network, including a second system for directing the cabling interconnections of the first system and, in each processor unit of the first system, a device access controller connected through a second network to a second system, each device access controller including a memory for storing a unique identifier, and a network controller to interconnect to a network controller of at least one other processor unit. There is a selectably settable anchor bit indicator to indicate a processor unit selected as a first processor unit of the first network, a next connection indicator connected from the device access controller, and connected from the network controller, a transmit test indicator connected from the device access controller and a receive indicator connected from the device access controller.