Compaq AlphaServer GS80 User Manual page 143

SCM Firmware
SCM firmware resides on the standard I/O module in flash memory. If the SCM
firmware should ever become corrupted or obsolete, you can update it manually
using the Loadable Firmware Update Utility. The microprocessor can also
communicate with the system power control logic to turn on or turn off power to
the rest of the system.
The SCM is powered by an auxiliary 5V supply. You can gain access to the
SCM as long as AC power is available to the system (through the wall outlet)
and the control panel keyswitch is in the On position. Thus, if the system fails,
you can still access the SCM and gather information about the failure.
PSMs, PBMs, and HPMs
The power system managers (PSMs), PCI backplane managers (PBMs), and
hierarchical switch power manager (HPM) are the "slaves" of the master SCM.
The SCM gathers all environmental data from the slaves. The PSMs, PBMs,
and HPM perform the following:
•
Monitors environmental sensors
•
Monitors voltages, power supplies, and fans
•
Shuts down a subsystem (QBB or PCI box) if a fatal condition (temperature
reaches a fatal limit or a power failure occurs) is detected
Configuration, Error Log, and Asset Information
The SCM provides additional functionality to read and write configuration and
error log information to FRU error log devices. All reading and writing of the
FRU EEPROMs is done by the slaves under the direction of the SCM.
Using the System Control Manager 8-5