HP (Hewlett-Packard) MAY21J8412 Personal Computer User Manual


 
8-4 www.hp.com Technical Reference Guide
System BIOS
8.3.3 Memory Detection and Configuration
This system uses the Serial Presence Detect (SPD) method of determining the installed DIMM
configuration. The BIOS communicates with an EEPROM on each DIMM through the SMBus
to obtain data on the following DIMM parameters:
Presence
Size
Type
Timing/CAS latency
Refer to Chapter 3, “Processor/Memory Subsystem” for the SPD format and DIMM data specific
to this system.
The BIOS performs memory detection and configuration with the following steps:
1. Program the buffer strength control registers based on SPD data and the DIMM slots that are
populated.
2. Determine the common CAS latency that can be supported by the DIMMs.
3. Determine the memory size for each DIMM and program the GMCH accordingly.
4. Enable refresh.
8.3.4 Boot Error Codes
The BIOS provides visual and audible indications of a failed system boot by using the system’s
power LED and the system board speaker. The error conditions are listed in the following table.