Service manual

System Overview 1-27
The system control manager (SCM) uses the console serial bus to:
• Control system power-up
• Configure the system
• Monitor the system
• Update firmware
• Power on and power off the system, locally or remotely
• Halt and reset the system
Through a microprocessor and its associated resources, the SCM receives and initiates
secure remote connections. It is powered by the Vaux output of the PCI power supply
that is on whenever AC is applied to the PCI box.
Figure 1–12 shows the hardware interfaces to the SCM:
• COM1 port or Super I/O (DVD/CD-ROM, mouse, keyboard, SCSI disk, etc.) COM1 is
an internal port to the ISA bus and is not brought outside the master PCI box.
• Modem port
• Local terminal port
• Operator control panel (OCP) switch, display, and LEDs
• Console serial bus (CSB)
• Shared RAM (shared between the SCM and SRM console/OS through the standard
I/O ISA bus) for storage of systemwide configuration and status, and for buffering
console data
The SCM has access to the following resources:
• 128 Kbytes of operating RAM
• 256 Kbytes of sector-erasable-flash EPROM for instruction storage
• 8 Kbytes of EEPROM for storage of configuration, error information, and user-
definable console settings
• 128 Kbytes of shared RAM
The SCM can operate in different modes allowing local or remote control. For a complete
description of the features available in the SCM, see the AlphaServer GS80/160/320
User’s Guide or the AlphaServer GS80/160/320 Firmware Reference Manual.
See Section 1.21.4 for a description of the standard I/O module where the SCM monitor
resides.