5 Troubleshooting
142
Diagnostic POST code LEDs
During the system boot process, BIOS executes a number of platform
configuration processes, each of which is assigned a specific hex code
number. As each configuration routine is started, BIOS will display the
given POST code to the diagnostic POST code LEDs found on the rear of
the mainboard. To assist in troubleshooting a system hang during the
POST process, the diagnostic LEDs can be used to identify the last POST
process to be executed.
Each POST code will be represented by a combination of colors from
the four LEDs. The LEDs are capable of displaying three colors: green,
red, and amber. Each bit in the upper nibble is represented by a red
LED and each bit in the lower nibble is represented by a green LED. If
both bits are set in the upper and lower nibbles then both red and
green LEDs are lit, resulting in an amber color. If both bits are clear,
then the LED is off.
Diagnostic LED placement diagram
The following table lists the possible POST codes that may be displayed
on the Diagnostic POST code LEDs during system initialization.
Checkpoint
code
Diagnostic LED Decoder
Description
G=Green, R=Red, A=Amber
MSB
LSB
Host Processor
0x10h
OFF
OFF
OFF
R
Power-on initialization of the host
processor (bootstrap processor)
0x11h
OFF
OFF
OFF
A
Host processor cache initialization
(including AP)
0x12h
OFF
OFF
G
R
Starting application processor
initialization
LSB
MSB
Back edge of server board
USB Port
USB Port
Diagnostic LEDs
Summary of Contents for Network Device Altos R520
Page 1: ...Acer Altos R520 Series User s Guide...
Page 10: ...x...
Page 11: ...1 System tour...
Page 38: ...1 System tour 28...
Page 39: ...2 System setup...
Page 47: ...3 System upgrade...
Page 99: ...4 BIOS setup...
Page 136: ...4 BIOS setup 126...
Page 137: ...5 Troubleshooting...
Page 158: ...5 Troubleshooting 148...
Page 159: ...Appendix A Acer Altos R520 rack installation guide...
Page 160: ...This appendix shows you how to set up the Acer Altos R520 server in a rack mount configuration...
Page 172: ...Appendix A Acer Altos R520 rack installation guide 162...
Page 173: ...Appendix B RAID configuration...
Page 184: ...174...