System Board
Input/output Controller Hub 2 (82801BA)
Chapter 2
51
RIMM Sockets
Each RIMM socket is connected to the SMBus. The 168-pin RIMM modules include a
256-byte I2C serial EEPROM. The first 128 bytes contain general information, including
the DRAM chips’ manufacturer’s name, RIMM speed rating, RIMM type, and so on. You
can use the second 128 bytes of the serial EEPROM to store data online.
AS98127F
The AS98127 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 nonvolatile memory that holds the default values for the CMOS memory (in
the event of battery failure).When you install a new system board, the serial EEPROM
will have a blank serial number field. The BIOS automatically detects this, and the
system prompts you for the serial number printed on the identification label on the back
of the workstation.
The computer uses 16KB of serial EEPROM implemented within two chips. Serial
EEPROM is ROM in which the application of appropriate electrical signals can return
one byte at a time to its unprogrammed state. In effect, you can make serial EEPROM
behave like very slow, nonvolatile RAM. It is used for storing the tattoo 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 reside on the system board. The sensor
measures the temperature in various areas of the system board. The system uses this
information to regulate fans.
HP MaxiLife Hardware-monitoring Chip
MaxiLife is a hardware-monitoring chip on the system board. Its functions include:
• On/off and reset control
• Status panel management (lock button, LEDs)
• Hardware monitoring (temperature and voltage)
• Early diagnostics (CPU, memory, PLLs, boot start)
• Run-time diagnostics (CPU errors)
• Fan speed regulation
• Other miscellaneous functions (such as special OK/FAIL symbols based on a smiling
face)
Figure 2-11 HP MaxiLife Hardware-Monitoring Chip
