Intel S2600GZ S2600GZ/GL - Page 244

Intel® Server Board S2600GZ/GL TPS Appendix D: POST Code Diagnostic LED Decoder Appendix D: POST Code Diagnostic LED Decoder As an aid to assist in trouble shooting a system hang that occurs during a system's Power-On Self Test (POST) process, the server board includes a bank of eight POST Code Diagnostic LEDs on the back edge of the server board. During the system boot process, Memory Reference Code (MRC) and System BIOS execute a number of memory initialization and platform configuration processes, each of which is assigned a specific hex POST code number. As each routine is started, the given POST code number is displayed to the POST Code Diagnostic LEDs on the back edge of the server board. During a POST system hang, the displayed post code can be used to identify the last POST routine that was run prior to the error occurring, helping to isolate the possible cause of the hang condition. Each POST code is represented by eight LEDs; four Green and four Amber. The POST codes are divided into two nibbles, an upper nibble and a lower nibble. The upper nibble bits are represented by Amber Diagnostic LEDs #4, #5, #6, #7. The lower nibble bits are represented by Green Diagnostics LEDs #0, #1, #2 and #3. If the bit is set in the upper and lower nibbles, the corresponding LED is lit. If the bit is clear, the corresponding LED is off. Figure 68. POST Diagnostic LED Location 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 Revision 1.1 231 Intel order number G24881-004