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Appendix C: POST Code Diagnostic LED DecoderIntel® Server Boards S5000PSL and S5000XSL TPS
In the below example, BIOS sends a value of ACh to the diagnostic LED decoder. The LEDs
are decoded as follows:
Red bits = 1010b = Ah
Green bits = 1100b = Ch
Since the red bits correspond to the upper nibble and the green bits correspond to the lower
nibble, the two are concatenated as ACh.
Table 47. POST Progress Code LED Example
8h 4h 2h 1h
LEDs Red Green Red Green Red Green Red Green
ACh 1 1 0 1 1 0 0 0
Result Amber Green Red Off
MSB Bit 2 Bit 1 LSB
Table 48. Diagnostic LED POST Code Decoder
Diagnostic LED Decoder
G=Green, R=Red, A=Amber
Checkpoint
MSB Bit 2 Bit 1 LSB
Description
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
0x13h Off Off G A SMM initialization
Chipset
0x21h Off Off R G Initializing a chipset component
Memory
0x22h Off Off A Off Reading configuration data from memory (SPD on DIMM)
0x23h Off Off A G Detecting presence of memory
0x24h Off G R Off Programming timing parameters in the memory controller
0x25h Off G R G Configuring memory parameters in the memory controller
0x26h Off G A Off Optimizing memory controller settings
0x27h Off G A G Initializing memory, such as ECC init
0x28h G Off R Off Testing memory
PCI Bus
0x50h Off R Off R Enumerating PCI busses
0x51h Off R Off A Allocating resources to PCI busses
0x52h Off R G R Hot Plug PCI controller initialization
0x53h Off R G A Reserved for PCI bus
0x54h Off A Off R Reserved for PCI bus
0x55h Off A Off A Reserved for PCI bus
0x56h Off A G R Reserved for PCI bus
Revision 1.2
Intel order number: D41763-003
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