HP Notebook 100 Compaq Armada 100S and Notebook 100 Series Maintenance and Ser - Page 34

Power-On Self Test (POST), Description

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2.3 Power-On Self Test (POST) When the computer starts, the system BIOS runs a series of internal checks on the hardware. This allows the computer to detect problems as early as the power-on stage. The POST alerts you to problems by displaying error messages. If POST detects an error, the system displays an error message on the display. If the error occurs before the display comes up, error codes or system beeps indicate the POST error. The value for diagnostic POST (378H) is written at the beginning of the test. Therefore, if the test fails, you can determine where the problem occurred by reading the last value written to POST 378H by the PIO Debug Board Plug at the PIO port. The following table lists error codes in sequential order on the PIO Debug Board. Code 01h 02h 03h 04h 05h 06h 07h 08h 09h 0Ah 0Bh 0Ch 0Fh 10h 11h Table 2-1 Error Codes Description Start of boot loader sequence. Initialize chipset. Memory sizing. Perform conventional RAM (1st 640K) test with crossed pattern R/W. Move boot loader to the RAM. Start point of execution of boot loader in RAM. Shadow screen BIOS. Initialize clock synthesizer. Initialize audio controller. Detect internal ISA modem. Proceed with normal boot. Proceed with crisis boot. DRAM sizing. Initial L1, L2 cache, make stack and diagnose. Turn off fast A20 for POST, Reset GDT's, 8259's quickly. continued 2-2 Troubleshooting

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2
-
2
Troubleshooting
2.3
Power-On Self Test (POST)
When the computer starts, the system BIOS runs a series of internal
checks on the hardware. This allows the computer to detect problems as
early as the power-on stage. The POST alerts you to problems by
displaying error messages.
If POST detects an error, the system displays an error message on the
display. If the error occurs before the display comes up, error codes or
system beeps indicate the POST error.
The value for diagnostic POST (378H) is written at the beginning of the
test. Therefore, if the test fails, you can determine where the problem
occurred by reading the last value written to POST 378H by the PIO
Debug Board Plug at the PIO port. The following table lists error codes
in sequential order on the PIO Debug Board.
Table 2-1
Error Codes
Code
Description
01h
Start of boot loader sequence.
02h
Initialize chipset.
03h
Memory sizing.
04h
Perform conventional RAM (1
st
640K) test with crossed pattern R/W.
05h
Move boot loader to the RAM.
06h
Start point of execution of boot loader in RAM.
07h
Shadow screen BIOS.
08h
Initialize clock synthesizer.
09h
Initialize audio controller.
0Ah
Detect internal ISA modem.
0Bh
Proceed with normal boot.
0Ch
Proceed with crisis boot.
0Fh
DRAM sizing.
10h
Initial L1, L2 cache, make stack and diagnose.
11h
Turn off fast A20 for POST, Reset GDT’s, 8259’s quickly.
continued