Technical Product Specification

Intel® Server Boards S4600LH2/T2 TPS Appendix D: POST Code Diagnostic LED Decoder
Revision 2.0
231
In the following example, the BIOS sends a value of ACh to the diagnostic LED decoder. The LEDs are
decoded as follows:
Note: Diag LEDs are best read and decoded when viewing the LEDs from the back of the system
Table 70. 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.
The following table provides a list of all POST progress codes.
Table 71. POST Progress Codes
Checkpoint
Diagnostic LED Decoder
Description
1 = LED On, 0 = LED Off
Upper Nibble
Lower Nibble
MSB
LSB
8h
4h
2h
1h
8h
4h
2h
1h
LED #
#7
#6
#5
#4
#3
#2
#1
#0
SEC Phase
01h
0
0
0
0
0
0
0
1
First POST code after CPU reset
02h
0
0
0
0
0
0
1
0
Microcode load begin
03h
0
0
0
0
0
0
1
1
CRAM initialization begin
04h
0
0
0
0
0
1
0
0
Pei Cache When Disabled
05h
0
0
0
0
0
1
0
1
SEC Core At Power On Begin.
06h
0
0
0
0
0
1
1
0
Early CPU initialization during Sec Phase.
07h
0
0
0
0
0
1
1
1
Early SB initialization during Sec Phase.
08h
0
0
0
0
1
0
0
0
Early NB initialization during Sec Phase.
09h
0
0
0
0
1
0
0
1
End Of Sec Phase.
0Eh
0
0
0
0
1
1
1
0
Microcode Not Found.
0Fh
0
0
0
0
1
1
1
1
Microcode Not Loaded.
PEI Phase
10h
0
0
0
1
0
0
0
0
PEI Core
11h
0
0
0
1
0
0
0
1
CPU PEIM
15h
0
0
0
1
0
1
0
1
NB PEIM
19h
0
0
0
1
1
0
0
1
SB PEIM
MRC Process Codes – MRC Progress Code Sequence is executed - See Table 58
PEI Phase continued…
31h
0
0
1
1
0
0
0
1
Memory Installed