Error Messages and Indicators
73
Port 80h POST Codes
During the POST, the BIOS generates diagnostic progress codes (POST codes) to I/O
port 80h. If the POST fails, execution stops and the last POST code generated is left
at port 80h and displayed on the Desktop Board’s seven-segment LED display shown
in Figure 31. This code is useful for determining the point where an e
rror occurred
during the
POST.
Figure 31. POST Code LED Display
Table 19 lists the Port 80h POST codes in hexadecimal notation.
Table 19. Port 80h POST Codes
POST Code Description
ACPI S States
00 Entering S0 state, standard
01-05 Entering S1-S5 state
10, 20, 30,
40, 50
Resuming from S1-S5 state
Security Phase (SEC)
08 Starting BIOS execution after CPU BIST
09 SPI prefetching and caching
0A, 0B Load BSP/APS microcode
0C Platform program base addresses
0D Wake up all APS
0E Initialize NEM
0F Pass entry point of the PEI core
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