POST Beep Codes

GUIDE: POST Beep Codes

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When you turn the computer on, it performs Power On System Test (POST), during which it checks and initializes the system’s internal components.
If a serious error occurs, the computer does not display a message but emits a series of long and short beeps instead.
Beeps are your computer’s way of letting you know what’s going on when the video signal is not working.
These codes are built in to the BIOS of the PC.
There is no official standard for these codes due to the many brands of BIOS that are out there.

To decode the meaning of your computer POST beep codes you must consult the manual of your motherboard.
If you don’t have a motherboard manual or if it’s incomplete you must search on the site of your computer manufacturer.
Another way is take off the computer case and look for BIOS manufacturer (just see if it says “AMI” or “Phoenix” …).
For more information about BIOS and how to identify it please check this site: Wim’s BIOS Page - Everything you want to know about BIOS.
Once you have determined your BIOS make, consult the following tables to see what’s wrong with your computer.


American Megatrends’ AMI BIOS

1The memory refresh circuitry has failed
2Parity errors have been detected in the first 64 KB of memory
3A failure has occurred within the first 64 KB or memory
4System Timer failure: Timer 1 on the mainboard does not work properly
5The CPU has generated an undetectable error
68042 Gate-A20 failure: BIOS cannot switch the CPU into protected mode
7The CPU has generated an exception error
8The video adapter is missing, or the memory on the adapter has generated a failure
9The ROM checksum value does not match the value in BIOS
10The shutdown register for CMOS interrupt channel 2 has failed POST; the system board cannot retrieve CMOS contents during POST
11Level-2 cache memory has failed the tests, and has been disabled
2 shortPOST has failed, caused by a failure of one of the hardware tests
1 long, 2 shortFailure in video system: a checksum error was encountered in video BIOS ROM, or a horizontal retrace failure has been encountered
1 long, 3 shortFailure in video system: the video DAC, the monitor detection procedure or the video RAM has failed
1 longPOST procedures have passed


The following are AMI BIOS Beep Codes that can occur. However because of the wide variety of different computer manufacturers with this BIOS the beep codes may vary.

Beep CodeDescriptions
1 shortDRAM refresh failure
2 shortParity circuit failure
3 shortBase 64K RAM failure
4 shortSystem timer failure
5 shortProcess failure
6 shortKeyboard controller Gate A20 error
7 shortVirtual mode exception error
8 shortDisplay memory Read/Write test failure
9 shortROM BIOS checksum failure
10 shortCMOS shutdown Read/Write error
11 shortCache Memory error
1 long, 3 shortConventional/Extended memory failure
1 long, 8 shortDisplay/Retrace test failed

AST Research BIOS

Long BeepShort BeepDescriptions
01Low level processor verification test failed (POST 1)
02Clearing keyboard controller buffers failed (POST 2)
03Keyboard controller reset failed (POST 3)
04Low level keyboard controller interface test (POST 4)
05Reading data from keyboard controller failed (POST 5)
06System board support chip initialization failed (POST 6)
07Processor register read/write verify test failed (POST 7)
08CMOS timer initialization failed (POST 8)
09ROM BIOS checksum test failed (POST 9)
010Initialize primary video (POST 10)
0118254 timer channel 0 test failed (POST 11)
0128254 timer channel 1 test failed (POST 12)
0138254 timer channel 2 test failed (POST 13)
014CMOS power-on and time test failed (POST 14)
015CMOS shutdown byte test failed (POST 15)
10DMA channel 0 test failed (POST 16)
11DMA channel 1 test failed (POST 17)
12DMA page register test failed (POST 18)
13Keyboard controller interface test failed (POST 19)
14Memory refresh toggle test failed (POST 20)
15First 64 KB memory test failed (POST 21)
16Setup interrupt vector table failed (POST 22)
17Video initialization failed (POST 23)
18Video memory test failed (POST 24)

AST Enhanced BIOS

Short BeepLong BeepShort BeepDescriptions
31-Flash loader failure
32-Failure in system board component
33-Failure in system board component
34-Memory failure
35-Video failure
06-Flash BIOS update error
-2xAST low level diagnostics

AST Phoenix BIOS

1-1-3CMOS read/write failure
1-1-4ROM BIOS checksum failure
1-2-1Programmable interval timer failure
1-2-2DMA initialization failure
1-2-3DMA page register read/write failure
1-3-1RAM refresh verification failure
1-3-3First 64 KB RAM chip or data or data line failure
1-3-4First 64 KB RAM odd/even logic failure
1-4-1First 64 KB RAM address line failure
1-4-2First 64 KB RAM parity failure
2-1-1First 64 KB RAM failure bit 0
2-1-2First 64 KB RAM failure bit 1
2-1-3First 64 KB RAM failure bit 2
2-1-4First 64 KB RAM failure bit 3
2-2-1First 64 KB RAM failure bit 4
2-2-2First 64 KB RAM failure bit 5
2-2-3First 64 KB RAM failure bit 6
2-2-4First 64 KB RAM failure bit 7
2-3-1First 64 KB RAM failure bit 8
2-3-2First 64 KB RAM failure bit 9
2-3-3First 64 KB RAM failure bit A
2-3-4First 64 KB RAM failure bit B
2-4-1First 64 KB RAM failure bit C
2-4-2First 64 KB RAM failure bit D
2-4-3First 64 KB RAM failure bit E
2-4-4First 64 KB RAM failure bit F
3-1-1Slave DMA register failure
3-1-2Master DMA register failure
3-1-3Slave interrupt mask register failure
3-1-4Slave interrupt mask failure
3-2-4Keyboard controller test failure
3-3-4Screen memory test failure
3-4-1Screen initialization failure
3-4-2Screen retrace test failure
3-4-3Failure searching for video ROM
4-2-1No timer tick
4-2-3Gate-A20 failure
4-2-4Unexpected interrupt in protected mode


BeepsError MessageDescriptionResolution
1Refresh FailureThe memory refresh circuitry is faulty.Reseat the memory SIMMs. If the system still beeps, replace the memory.
2Parity ErrorParity error in the base memory (the first 64 KB block) of memory. Reseat the memory SIMMs. If the system still beeps, replace the memory.
3Base 64 KB Memory FailureMemory failure in first 64 KB.Reseat the memory SIMMs. If the system still beeps, replace the memory.
4Timer Not OperationalA memory failure in the first 64 KB of memory, or Timer 1 is not functioning.The motherboard must be replaced.
5Processor error 8042 - Gate A20 FailureThe CPU generated an error.The motherboard must be replaced.
68042 - Gate A20 Failure Processor Exception Interrupt ErrorCannot switch to protected mode.Try a different keyboard, or replace the keyboard fuse, if the keyboard has one.
7Processor Exception Interrupt ErrorThe CPU on the CPU Card generated an exception interrupt.The motherboard must be replaced.
8Display Memory Read/Write ErrorThe system video adapter is either missing or its memory is faulty. This is not a fatal error.There is a memory error on the video adapter. Replace the video adapter, or the RAM on the video adapter.
9ROM Checksum ErrorThe ROM checksum value does not match the value encoded in WINBIOS.The BIOS ROM chip is bad. The system probably needs a new BIOS ROM chip.
10CMOS Shutdown Register Read/Write ErrorThe shutdown register for CMOS RAM has failed.The motherboard must be replaced.
11Cache memory bad - do not enable cacheThe cache memory test failed. Cache memory is disabled. Do not press Ctrl/Alt/Shift <+> to enable cache memory.The motherboard must be replaced.


The following are Award BIOS Beep Codes that can occur. However because of the wide variety of different computer manufacturers with this BIOS the beep codes may vary.

Beep CodeDescriptions
1 long, 2 shortIndicates a video error has occurred and the BIOS cannot initialize the video screen to display any additional information
Any other beep(s)>RAM problem.

If any other correctable hardware issues the BIOS will display a message.


The following are IBM BIOS Beep Codes that can occur. However because of the wide variety of models shipping with this BIOS the beep codes may vary.

Beep CodeDescriptions
No BeepsNo Power, Loose Card, or Short.
1 Short BeepNormal POST, computer is ok.
2 Short BeepPOST error, review screen for error code.
Continuous BeepNo Power, Loose Card, or Short.
Repeating Short BeepNo Power, Loose Card, or Short.
One Long and one Short BeepMotherboard issue.
One Long and Two short BeepsVideo (Mono/CGA Display Circuitry) issue.
One Long and Three Short Beeps.Video (EGA) Display Circuitry.
Three Long BeepsKeyboard / Keyboard card error.
One Beep, Blank or Incorrect DisplayVideo Display Circuitry.


Error Tone. (two sets of different tones)Problem with logic board or SCSI bus.
Startup tone, drive spins, no videoProblem with video controller.
Powers on, no tone.Logic board problem.
High Tone, four higher tones.Problem with SIMM.



Beep CodeDescriptions / What to Check
1-1-1-3Verify Real Mode.
1-1-2-1Get CPU type.
1-1-2-3Initialize system hardware.
1-1-3-1Initialize chipset registers with initial POST values.
1-1-3-2Set in POST flag.
1-1-3-3Initialize CPU registers.
1-1-4-1Initialize cache to initial POST values.
1-1-4-3Initialize I/O.
1-2-1-1Initialize Power Management.
1-2-1-2Load alternate registers with initial POST values.
1-2-1-3Jump to UserPatch0.
1-2-2-1Initialize keyboard controller.
1-2-2-3BIOS ROM checksum.
1-2-3-18254 timer initialization.
1-2-3-38237 DMA controller initialization.
1-2-4-1Reset Programmable Interrupt Controller.
1-3-1-1Test DRAM refresh.
1-3-1-3Test 8742 Keyboard Controller.
1-3-2-1Set ES segment to register to 4 GB.
1-3-3-128 Autosize DRAM.
1-3-3-3Clear 512K base RAM.
1-3-4-1Test 512 base address lines.
1-3-4-3Test 512K base memory.
1-4-1-3Test CPU bus-clock frequency.
1-4-2-4Reinitialize the chipset.
1-4-3-1Shadow system BIOS ROM.
1-4-3-2Reinitialize the cache.
1-4-3-3Autosize cache.
1-4-4-1Configure advanced chipset registers.
1-4-4-2Load alternate registers with CMOS values.
2-1-1-1Set Initial CPU speed.
2-1-1-3Initialize interrupt vectors.
2-1-2-1Initialize BIOS interrupts.
2-1-2-3Check ROM copyright notice.
2-1-2-4Initialize manager for PCI Options ROMs.
2-1-3-1Check video configuration against CMOS.
2-1-3-2Initialize PCI bus and devices.
2-1-3-3Initialize all video adapters in system.
2-1-4-1Shadow video BIOS ROM.
2-1-4-3Display copyright notice.
2-2-1-1Display CPU type and speed.
2-2-1-3Test keyboard.
2-2-2-1Set key click if enabled.
2-2-2-356 Enable keyboard.
2-2-3-1Test for unexpected interrupts.
2-2-3-3Display prompt “Press F2 to enter SETUP”.
2-2-4-1Test RAM between 512 and 640k.
2-3-1-1Test expanded memory.
2-3-1-3Test extended memory address lines.
2-3-2-1Jump to UserPatch1.
2-3-2-3Configure advanced cache registers.
2-3-3-1Enable external and CPU caches.
2-3-3-3Display external cache size.
2-3-4-1Display shadow message.
2-3-4-3Display non-disposable segments.
2-4-1-1Display error messages.
2-4-1-3Check for configuration errors.
2-4-2-1Test real-time clock.
2-4-2-3Check for keyboard errors
2-4-4-1Set up hardware interrupts vectors.
2-4-4-3Test coprocessor if present.
3-1-1-1Disable onboard I/O ports.
3-1-1-3Detect and install external RS232 ports.
3-1-2-1Detect and install external parallel ports.
3-1-2-3Re-initialize onboard I/O ports.
3-1-3-1Initialize BIOS Data Area.
3-1-3-3Initialize Extended BIOS Data Area.
3-1-4-1Initialize floppy controller.
3-2-1-1Initialize hard-disk controller.
3-2-1-2Initialize local-bus hard-disk controller.
3-2-1-3Jump to UserPatch2.
3-2-2-1Disable A20 address line.
3-2-2-3Clear huge ES segment register.
3-2-3-1Search for option ROMs.
3-2-3-3Shadow option ROMs.
3-2-4-1Set up Power Management.
3-2-4-3Enable hardware interrupts.
3-3-1-1Set time of day.
3-3-1-3Check key lock.
3-3-3-1Erase F2 prompt.
3-3-3-3Scan for F2 key stroke.
3-3-4-1Enter SETUP.
3-3-4-3Clear in-POST flag.
3-4-1-1Check for errors
3-4-1-3POST done–prepare to boot operating system.
3-4-2-1One beep.
3-4-2-3Check password (optional).
3-4-3-1Clear global descriptor table.
3-4-4-1Clear parity checkers.
3-4-4-3Clear screen (optional).
3-4-4-4Check virus and backup reminders.
4-1-1-1Try to boot with INT 19.
4-2-1-1Interrupt handler error.
4-2-1-3Unknown interrupt error.
4-2-2-1Pending interrupt error.
4-2-2-3Initialize option ROM error.
4-2-3-1Shutdown error.
4-2-3-3Extended Block Move.
4-2-4-1Shutdown 10 error.
4-3-1-3Initialize the chipset.
4-3-1-4Initialize refresh counter.
4-3-2-1Check for Forced Flash.
4-3-2-2Check HW status of ROM.
4-3-2-3BIOS ROM is OK.
4-3-2-4Do a complete RAM test.
4-3-3-1Do OEM initialization.
4-3-3-2Initialize interrupt controller.
4-3-3-3Read in bootstrap code.
4-3-3-4Initialize all vectors.
4-3-4-1Boot the Flash program.
4-3-4-2Initialize the boot device.
4-3-4-3Boot code was read OK.


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