HP Kayak XU800 Series, Technical Reference Manual

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2 System Board
The Input/Output Controller Hub (82801AA)
ICH SMBus Master
Controller
The ICH provides a processor-to-SMBus controller. All access performed to
the SMBus is done through the ICH SMBus interface. Typically, the
processor has access to all the devices connected to the SMBus.
DIMM Sockets
Each DIMM socket is connected to the SMBus. The 168-pin DIMM modules
include a 256 byte I
2
C Serial EEPROM. The first 128 bytes contain general
information, including the DRAM chips’ manufacturer name, DIMM speed
rating, DIMM type, etc. The second 128 bytes of the Serial EEPROM can be
used to store data online.
RIMM Sockets
Each RIMM socket is connected to the SMBus. The 168-pin RIMM modules
include a 256 byte I
2
C Serial EEPROM. The first 128 bytes contain general
information, including the DRAM chips’ manufacturer name, RIMM speed
rating, RIMM type, etc. The second 128 bytes of the Serial EEPROM can be
used to store data online.
ADM1024
The ADM1024 chip is a hardware monitoring sensor dedicated to the
processor temperature. This chip uses the thermal diodes integrated into
each processor cartridge and makes the temperature information available
through the SMBus. It also monitors processor power supply voltages.
Serial EEPROM
This is the non-volatile memory which holds the default values for the CMOS
memory (in the event of battery failure).When installing a new system
board, the Serial EEPROM will have a blank serial number field. This will be
detected automatically by the BIOS, which will then prompt the user for the
serial number which is printed on the identification label on the back of the
PC Workstation. The computer uses 16KBytes of Serial EEPROM
implemented within two chips. Serial EEPROM is ROM in which one byte at
a time can be returned to its unprogrammed state by the application of
appropriate electrical signals. In effect, it can be made to behave like very
slow, non-volatile RAM. It is used for storing the tatoo string, the serial
number, and the parameter settings for the
Setup
program as well as
MaxiLife firmware.
LM75 Temperature
Sensor
The LM75 temperature sensor and alarm are located on the system board.
The sensor is used to measure the temperature in various areas of the
system board. This information is used to regulate fans.