Power-On Self-Test

Note

If Quiet Boot is enabled in BIOS Setup (the default setting), press ESC during boot to see POST messages.

The POST (Power-On Self-Test) is a series of initialization routines and diagnostic tests that the system BIOS runs when the computer boots. The system BIOS will not boot the operating system if system memory, the CPU, DMA, or the interrupt controller fails the POST diagnostic tests. POST progress is indicated by a sequence of codes. If possible, error messages are displayed.

You should not interpret the failure of one or more POST tests as a hardware, software, or firmware failure. First, confirm the failure with a “clean” boot:

∙Remove all accessories, including RAM boards, floppy drive, port replicator, PC Cards, printer, external monitor, pointing device, and keyboard.

∙Provide “clean” ac power—no auto adapter or unusual ac adapter configuration.

∙Press the system-off button to start from a known state.

If the computer fails to boot with a clean boot, it requires repair. If an error message is displayed, confirm the problem using other diagnostic tools. Not all POST messages indicate a hardware, software, or firmware failure—some messages are informational messages.

If the BIOS detects a terminal error condition, it halts POST after issuing a terminal error beep code— up to four groups of 1 to 4 short beeps. The beep code indicates the POST routine in which the terminal error occurred. The BIOS also issues a beep code (one long tone followed by two short tones) during POST if the video configuration fails (no card installed or faulty) or if an external ROM module does not properly checksum to zero.

Beep Codes

1

1-2

1-2-2-3

1-3-1-1

1-3-1-3

1-3-4-1

1-3-4-3

1-4-1-1

2-1-2-3

2-2-3-1

Table 3-4. POST Terminal-Error Beep Codes

POST Description

One short beep before boot

Search for option ROMs. One long, two short beeps on checksum failure

BIOS ROM checksum

Test DRAM refresh

Test 8742 Keyboard Controller

RAM failure on address line xxxx

RAM failure on data bits xxxx of low byte of memory bus

RAM failure on data bits xxxx of high byte of memory bus

Check ROM copyright notice

Test for unexpected interrupts

The following table lists POST messages and explanations for reported problems. If the system fails after you make changes in BIOS Setup, reset the computer, enter BIOS Setup, and install the defaults or correct the error.

3-16 Troubleshooting and Diagnostics

HP OmniBook 7100