Compaq 100 armada 100s Manuales De Servicio

Writer: David Calvert    Saved by: The Integrity Group    Saved date: 09/26/00 2:34 PM

Part Number: 177845-002    File name: Ch02

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.

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.