Service manual

1-22 AlphaServer GS80/160/320 Service Manual
1.8 System Management Architecture
AlphaServer GS80/160/320 systems use an independent multi-drop
serial bus, powered by auxiliary voltage (Vaux), to configure, monitor,
and control the system and its partitions either locally or remotely.
1.8.1 Console Serial Bus
The console serial bus (CSB) is controlled by the system control
manager microprocessor (SCM) on the standard I/O module in the
required master PCI box. Each QBB, PCI, standard I/O module with its
SCM, and hierarchical switch, if present, is connected to the CSB.
Figure 1– 10 Console Serial Bus Block Diagram
Figure 1–10 is a block diagram of the console serial bus. Vaux, present whenever AC is
applied, powers this bus and its nodes; it functions while the system is off (DC not
present). The master system control manager (SCM) controls the console serial bus.
The OCP can connect to two SCMs on two standard I/O modules providing redundancy.