BIOS POST Check Point List 4-33
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BIOS POST Check Point List
AMIBIOS provides all IBM standard Power On Self Test (POST) routines as well as enhanced
AMIBIOS POST routines. The POST routines support CPU internal diagnostics. The POST
checkpoint codes are accessible via the Manufacturing Test Port (I/O port 80h).
Whenever a recoverable error occurs during the POST, the system BIOS will display an error
message describing the message and explaining the problem in detail so that the problem can be
corrected.
During the POST, the BIOS signals a checkpoint by issuing one code to I/O address 80H. This
code can be used to establish how far the BIOS has executed through the power-on sequence
and what test is currently being performed. This is done to help troubleshoot a faulty system
board.
If the BIOS detects a terminal error condition, it will halt the POST process and attempt to
display the checkpoint code written to port 80H. If the system hangs before the BIOS detects
the terminal error, the value at port 80H will be the last test performed. In this case, the terminal
error cannot be displayed on the screen. The following POST checkpoint codes are valid for all
AMIBIOS products with a core BIOS date of 07/15/95 version 6.27 (Enhanced).
