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This chapter is from the book

How the BIOS Reports Errors

The BIOS uses three methods for reporting errors: beep codes, error/status codes, and onscreen messages. Error/status codes must be read with a special interface board, whereas the others require no special equipment.

BIOS Beep Codes and Their Purposes

Virtually all systems make a polite "beep" noise when started, but most systems have a special series of beep codes that serve the following purposes:

  • Beeps alert you to serious system problems, many of which can prevent your system from even starting (a so-called fatal error) or from working to its full potential (a so-called nonfatal error).

  • Because most fatal and many nonfatal errors take place before the video subsystem is initialized (or might indicate that the video isn't working), beeps can be used to determine the cause of the problem.

  • A system that can't start and is reporting a problem with beep codes will give the code once and then halt. To hear the code again, restart the computer.

Use the following tables of beep codes to determine why your system will not start. To solve the problem reported by the beep codes, repair or replace the device listed in the description. If your repair or replacement has solved the problem, the beep code will no longer sound when you restart the system.

For errors involving removable devices (socketed chips, memory, or video), an easy fix is to remove and replace the item because a device that's not securely in its socket will cause the test to fail.

Note

For an exhaustive list of BIOS codes, beep codes, and error messages, see the CD accompanying Upgrading and Repairing PCs, 13th Edition.

AMI BIOS Beep Codes and Solutions

Note

AMI BIOS beep codes are used by permission of American Megatrends, Inc.

Beeps

Error Message

Description

Explanation

1

DRAM Refresh Failure

The memory refresh circuitry on the motherboard is faulty.

Remove and reinstall memory, and retry. Replace memory with known working memory.

2

Parity Error

A parity error occurred in system memory.

Remove and reinstall memory, and retry. Replace memory with known working memory. Disable parity checking in BIOS if you are using nonparity memory.

3

Base 64K (First Bank)

Memory failure in the first bank of memory.

Remove and reinstall Memory Failure memory, and retry. Replace -memory with known working memory.

4

System Timer Failure

Memory failure in the first bank of memory, or Timer 1 on the motherboard is not functioning.

Remove and reinstall memory, and retry. Replace memory with known working memory. Replace motherboard if memory swap doesn't help.

5

Processor Error

The processor on the motherboard generated an error.

Remove and reinstall processor. Replace processor with known working processor. Replace motherboard if processor swap doesn't help.

6

Keyboard Controller Gate A20 Failure

The keyboard controller might be bad. The BIOS cannot switch to protected mode.

Remove and reinstall keyboard controller chip (if socketed). Replace and reinstall keyboard; look for blown keyboard fuse on motherboard and replace.

7

Virtual Mode Processor Exception Interrupt Error

The processor generated an exception interrupt.

Remove and reinstall processor. Replace processor with known working processor. Replace motherboard if processor swap doesn't help.

8

Display Memory Read/Write Error

Either the system video adapter is missing or its memory is faulty.

Remove and reinstall memory on video card (if memory removable). Remove and reinstall video card. Replace video card with known working unit.

9

ROM checksum Error

ROM Checksum value does not match the value encoded in BIOS.

Faulty BIOS chip; replace BIOS chip, if socketed, or replace motherboard.

10

CMOS Shutdown Register Read/Write Error

The shutdown register for CMOS RAM failed.

Replace motherboard.

11

Cache Error/L2 Cache Bad

The L2 cache is faulty.

Locate L2 cache. If built into processor, remove and reinstall processor. Replace processor with known working unit.

If built into motherboard, replace motherboard.

If socketed, remove and reinstall cache RAM chips or module. Replace with known working cache RAM or replace motherboard.

1 long, 3 short

Conventional/ extended memory failure

The motherboard memory is faulty.

Remove and reinstall memory, and retry. Replace memory with known working memory.

1 long, 8 short

Display/retrace test failure

The video card is faulty.

Reseat the video card in its slot, or move it to a different slot.


Award BIOS Beep Codes

Currently only one beep code exists in the Award BIOS. A single long beep followed by two short beeps indicates that a video error has occurred and the BIOS cannot initialize the video screen to display any additional information.

Phoenix BIOS Beep Codes

The following beep codes are for the current version of Phoenix BIOS, version 4.0, release 6. Other versions will have somewhat different beeps and Port 80h codes. To view the Port 80h codes, you will need a POST diagnostics card with a two-digit LED readout, available from many sources for diagnostic tools. I recommend a PCI-based POST card because ISA slots are becoming obsolete.

Note

Phoenix BIOS beep codes are used by permission of Phoenix Technologies, Ltd.

Beeps

Port 80h Code

Explanation

1-2-2-3

16h

BIOS ROM checksum

1-3-1-1

20h

Test DRAM refresh

1-3-1-3

22h

Test keyboard controller

1-3-3-1

28h

Autosize DRAM

1-3-3-2

29h

Initialize POST memory manager

1-3-3-3

2Ah

Clear 512KB base RAM

1-3-4-1

2Ch

RAM failure on address line xxxx

1-3-4-3

2Eh

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

1-4-1-1

30h

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

2-1-2-2

45h

POST device initialization

2-1-2-3

46h

Check ROM copyright notice

2-2-3-1

58h

Test for unexpected interrupts

2-2-4-1

5Ch

Test RAM between 512KB and 640KB

1-2

98h

-Search for option ROMs; one long, two short beeps on checksum failure

1

B4h

One short beep before boot


IBM BIOS Beep and Alphanumeric Error Codes

After completing the power-on self-test (POST), an audio code indicates either a normal condition or that one of several errors has occurred.

Note

IBM BIOS and alphanumeric error codes used by permission of IBM.

Audio Code

Sound Graph

Description

1 short beep

 

Normal POST—system okay

2 short beeps

 

POST error—error code on display

No beep

 

Power supply, system board

Continuous beep

—————

Power supply, system board

Repeating short beeps

 

Power supply,

 

 

system board

1 long, 1 short beep

System board

1 long, 2 short beeps

Video adapter (MDA/CGA)

1 long, 3 short beeps

Video adapter (EGA/VGA)

3 long beeps

———

3270 keyboard card

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