Intel R2000BB4GS9 Data Sheet
Intel
®
Server System R2000BB Product Family TPS
Revision 2.0
65
Appendix B: POST Code Diagnostic LED Decoder
As an aid to assist in trouble shooting a system hang that occurs during a system’s Power-On Self Test (POST)
process, the server board includes a bank of eight POST Code Diagnostic LEDs on the back edge of the
server board.
process, the server board includes a bank of eight POST Code Diagnostic LEDs on the back edge of the
server board.
During the system boot process, Memory Reference Code (MRC) and System BIOS execute a number of
memory initialization and platform configuration processes, each of which is assigned a specific hex POST
code number. As each routine is started, the given POST code number is displayed to the POST Code
Diagnostic LEDs on the back edge of the server board.
memory initialization and platform configuration processes, each of which is assigned a specific hex POST
code number. As each routine is started, the given POST code number is displayed to the POST Code
Diagnostic LEDs on the back edge of the server board.
During a POST system hang, the displayed post code can be used to identify the last POST routine that was
run prior to the error occurring, helping to isolate the possible cause of the hang condition.
run prior to the error occurring, helping to isolate the possible cause of the hang condition.
Each POST code is represented by eight LEDs; four Green and four Amber. The POST codes are divided into
two nibbles, an upper nibble and a lower nibble. The upper nibble bits are represented by Amber Diagnostic
LEDs #4, #5, #6, #7. The lower nibble bits are represented by Green Diagnostics LEDs #0, #1, #2 and #3. If
the bit is set in the upper and lower nibbles, the corresponding LED is lit. If the bit is clear, the corresponding
LED is off.
two nibbles, an upper nibble and a lower nibble. The upper nibble bits are represented by Amber Diagnostic
LEDs #4, #5, #6, #7. The lower nibble bits are represented by Green Diagnostics LEDs #0, #1, #2 and #3. If
the bit is set in the upper and lower nibbles, the corresponding LED is lit. If the bit is clear, the corresponding
LED is off.
Figure 52. POST Diagnostic LED Location
In the following example, the BIOS sends a value of ACh to the diagnostic LED decoder. The LEDs are
decoded as follows:
decoded as follows:
Table 27. POST Progress Code LED Example
LEDs
Upper Nibble AMBER LEDs
Lower Nibble GREEN LEDs
MSB
LSB
LED #7
LED #6
LED #5
LED #4
LED #3
LED #2
LED #1
LED #0
8h
4h
2h
1h
8h
4h
2h
1h
Status
ON
OFF
ON
OFF
ON
ON
OFF
OFF
Results
1
0
1
0
1
1
0
0
Ah
Ch
Upper nibble bits = 1010b = Ah; Lower nibble bits = 1100b = Ch; the two are concatenated as ACh.