Home > Articles > Hardware > Upgrading & Repairing

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.


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


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


Error Message




DRAM Refresh Failure

The memory refresh circuitry on the motherboard is faulty.

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


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.


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.


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.


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.


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.


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.


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.


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.


CMOS Shutdown Register Read/Write Error

The shutdown register for CMOS RAM failed.

Replace motherboard.


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.


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


Port 80h Code




BIOS ROM checksum



Test DRAM refresh



Test keyboard controller



Autosize DRAM



Initialize POST memory manager



Clear 512KB base RAM



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



POST device initialization



Check ROM copyright notice



Test for unexpected interrupts



Test RAM between 512KB and 640KB



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



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.


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

Audio Code

Sound Graph


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

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020