Port 80H Post Codes - Intel BOXD5400XS Product Manual

Intel Desktop Board D5400XS Product Guide

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 29. This code is useful for determining the point where an error occurred
during the POST.
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Figure 29. POST Code Indicators