MAXDATA PLATINUM Server Board User’s Manual
88
Diagnostic LEDs
To help diagnose POST failures, a set of four bi-color diagnostic LEDs is located on the back
edge of the baseboard. Each of the four LEDs can have one of four states: Off, Green, Red,
or Amber.
The LED diagnostics feature consists of a hardware decoder and four dual color LEDs. During
POST, the LEDs will display all normal Port80 codes representing the progress of the BIOS
POST. Each postcode will be represented by a combination of colors from the 4 LEDs. The
LEDs are in pairs of green and red. The post codes codes are broken into two nibbles, an
upper and a lower nibble. Each bit in the upper nibble is represented by a red LED and each
bit in the lower nibble is represented by a green LED. If both bits are set in the upper and
lower nibble then both red and green LEDs are lit, resulting in an amber color. Likewise, if
both bits are clear then the red and green LEDs are off.
During the POST process, each light sequence represents a specific Port-80 POST code. If a
system should hang during POST, the Diagnostic LEDs will present the last test executed
before the hang. When reading the lights, the LEDs should be observed from the back of the
system. The most significant bit (MSB) is the first LED on the left, and the least significant
bit (LSB) is the last LED on the right.
Note: When comparing a diagnostic LED color string from the baseboard to those listed in
the diagnostic LED decoder in the following tables, the LEDs on the baseboard should be
referenced when viewed by looking into the system from the back. Reading the LEDs from
left to right, the Hi bit is located on the left.
Table 11. Post Codes
Post Code Diagnostic LED Decoder Description
G=Green, R=Red, A=Amber
MSB LSB
07h Off G G G Uncompress various BIOS Modules
08h G Off Off Off Verify password Checksum
08h G Off Off Off Verify CMOS Checksum.
07h OffGGGRead Microcode updates from BIOS ROM.
07h Off G G G Initializing the processors. Set up processor registers. Select least
featured processor as the BSP.
0Bh G Off G G Hook before the keyboard BAT command is issued.
0Ch G G Off Off Keyboard Controller Test: The keyboard controller input buffer is
free. Next, issuing the BAT command to the keyboard controller
0Eh GGGOffInit after Keyboard Test: The keyboard controller BAT
command result has been verified. Next, performing any
necessary initialization after the keyboard controller BAT
command test.
0Fh GGGGWrite Command Byte 8042: The initialization after the key
board controller BAT command test is done. The keyboard
command byte will be written next.
10h Off Off Off R Keyboard Init: The keyboard controller command byte is written.
Next, issuing the pin 23 and 24 blocking and unblocking com
mands
10h Off Off Off R Disable and initialize 8259
11h Off Off Off A Detect Configuration Mode, such as CMOS clear.
13h Off Off G A Chipset Initialization before CMOS initialization
continued
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