During LAT System Initialization the most important objective is to establish communications with the ground as early as possible. To that end the SIB is configured immediately following the configuration of the Director SBC.
The exact configuration of the SIB is beyond the scope of this document, but at minimum the PCI bus configuration ( described in Section 1.2) for the SIB is performed at this point.
Subsequent to the PCI configuration of the SIB the Director SBC enables the SIB for business.