When troubleshooting computers, you may run into an archaic type of system, or even new. When the machine is turned on, there is no display, but the computer gives a series of beeps instead. This is a guide for determining what each code means, especially for the three most popular BIOS manufacturers:

American Megatrends, Inc.

This will not cover all the BIOS manufacturers out there, since there would probably not be enough space to do so. If your BIOS is made by a company other than the ones above, try to do a Google search for them. Also, this will cover the most beep codes as there are some specialized errors that have different beep patterns than the short consecutive patterns that are the most common.


1 Long Beep: Memory problem
1 Long, then 2 Short Beeps: Video error
1 Long, then 3 Short Beeps: Video error
Continuous Beeping: Memory or video problem

American Megatrends, Inc.

1 Beep: DRAM refresh failure
2 Beeps: Parity circuit failure
3 Beeps: Base 64K RAM failure
4 Beeps: System timer failure
5 Beeps: Processor failure
6 Beeps: Keyboard controller / gate A20 failure
7 Beeps: Virtual mode exception error
8 Beeps: Display memory read/write failure
9 Beeps: ROM BIOS checksum failure
10 Beeps: CMOS shutdown register read/write error
11 Beeps: Cache memory error
Continuous Beeping: Memory or video problem


Note: The Phoenix list is quite extensive and is divided into 2 categories: ≥4.0 and <4.0 (pre 1994).

<4.0 (pre 1994).

1-1-3 (02h): CMOS write/read test failure
1-1-4 (03h): BIOS ROM checksum failure
1-2-1 (04h): Programmable interval timer test failure
1-2-2 (05h): DMA initialization failure
1-2-3 (06h): DMA page register write/read test failure
1-3-1 (08h): RAM refresh verification failure
1-3-3 (0Ah): 1st 64K RAM chip or data line failure - multi-bit
1-3-4 (0Bh): 1st 64K RAM odd/even logic failure
1-4-1 (0Ch): 1st 64K RAM address line failure
1-4-2 (0Dh): 1st 64K RAM parity test in progress or failure
2-1-1 (10h): 1st 64K RAM chip or data line failure - bit 0
2-1-2 (11h): 1st 64K RAM chip or data line failure - bit 1
2-1-3 (12h): 1st 64K RAM chip or data line failure - bit 2
2-1-4 (13h): 1st 64K RAM chip or data line failure - bit 3
2-2-1 (14h): 1st 64K RAM chip or data line failure - bit 4
2-2-2 (15h): 1st 64K RAM chip or data line failure - bit 5
2-2-3 (16h): 1st 64K RAM chip or data line failure - bit 6
2-2-4 (17h): 1st 64K RAM chip or data line failure - bit 7
2-3-1 (18h): 1st 64K RAM chip or data line failure - bit 8
2-3-2 (19h): 1st 64K RAM chip or data line failure - bit 9
2-3-3 (1Ah): 1st 64K RAM chip or data line failure - bit A
2-3-4 (1Bh): 1st 64K RAM chip or data line failure - bit B
2-4-1 (1Ch): 1st 64K RAM chip or data line failure - bit C
2-4-2 (1Dh): 1st 64K RAM chip or data line failure - bit D
2-4-3 (1Eh): 1st 64K RAM chip or data line failure - bit E
2-4-4 (1Fh): 1st 64K RAM chip or data line failure - bit F
3-1-1 (20h): Master DMA register test failure
3-1-2 (21h): Slave DMA register test failure
3-1-3 (22h): Master interrupt mask register test failure
3-1-4 (23h): Slave interrupt mask register test failure
3-2-4 (27h): Keyboard controller test failure
3-3-4 (2Bh): Screen memory test failure
3-4-1 (2Ch): Screen initialization failure
3-4-2 (2Dh): Screen retrace test failure
4-2-1 (34h): Timer tick interrupt test failure
4-2-2 (35h): Shutdown test failure
4-2-3 (36h): Gate A20 failure
4-2-4 (37h): Unexpected interrupt in protected mode
4-3-1 (38h): RAM test failure above address 0FFFFh
4-3-3 (3Ah): Interval timer channel 2 test failure
4-3-4 (3Bh): Time-Of-Day clock test failure
4-4-1 (3Ch): Serial port test failure
4-4-2 (3Dh): Parallel port test failure
4-4-3 (3Eh): Math coprocessor test failure


1-1-1-3 (02h): Verify real mode
1-1-2-1 (04h): Get CPU type
1-1-2-3 (06h): Initialize system hardware
1-1-3-1 (08h): Initialize chipset registers with initial POST values
1-1-3-2 (09h): Set in POST flag
1-1-3-3 (0Ah): Initialize CPU registers
1-1-4-1 (0Ch): Initialize cache to initial POST values
1-1-4-3 (0Eh): Initialize I/O
1-2-1-1 (10h): Initialize Power Management
1-2-1-2 (11h): Load alternate registers with initial POST values
1-2-1-3 (12h): Jump to UserPatch0
1-2-2-1 (14h): Initialize keyboard controller
1-2-2-3 (16h): BIOS ROM checksum
1-2-3-1 (18h): 8254 timer initialization
1-2-3-3 (1Ah): 8237 DMA controller initialization
1-2-4-1 (1Ch): Reset Programmable Interrupt Controller
1-3-1-1 (20h): Test DRAM refresh
1-3-1-3 (22h): Test 8742 Keyboard Controller
1-3-2-1 (24h): Set ES segment register to 4 GB
1-3-3-1 (28h): Autosize DRAM
1-3-3-3 (2Ah): Clear 512K base RAM
1-3-4-1 (2Ch): Test 512 base address lines
1-3-4-3 (2Eh): Test 512K base memory
1-4-1-3 (32h): Test CPU bus-clock frequency
1-4-2-1 (34h): CMOS RAM read/write failure
1-4-2-4 (37h): Reinitialize the chipset
1-4-3-1 (38h): Shadow system BIOS ROM
1-4-3-2 (39h): Reinitialize the cache
1-4-3-3 (3Ah): Autosize cache
1-4-4-1 (3Ch): Configure advanced chipset registers
1-4-4-2 (3Dh): Load alternate registers with CMOS values
2-1-1-1 (40h): Set Initial CPU speed
2-1-1-3 (42h): Initialize interrupt vectors
2-1-2-1 (44h): Initialize BIOS interrupts
2-1-2-3 (46h): Check ROM copyright notice
2-1-2-4 (47h): Initialize manager for PCI Options ROMs
2-1-3-1 (48h): Check video configuration against CMOS
2-1-3-2 (49h): Initialize PCI bus and devices
2-1-3-3 (4Ah): Initialize all video adapters in system
2-1-4-1 (4Ch): Shadow video BIOS ROM
2-1-4-3 (4Eh): Display copyright notice
2-2-1-1 (50h): Display CPU type and speed
2-2-1-3 (52h): Test keyboard
2-2-2-1 (54h): Set key click if enabled
2-2-2-3 (56h): Enable keyboard
2-2-3-1 (58h): Test for unexpected interrupts
2-2-3-3 (5Ah): Display prompt "Press F2 to enter SETUP"
2-2-4-1 (5Ch): Test RAM between 512 and 640k
2-3-1-1 (60h): Test expanded memory
2-3-1-3 (62h): Test extended memory address lines
2-3-2-1 (64h): Jump to UserPatch1
2-3-2-3 (66h): Configure advanced cache registers
2-3-3-1 (68h): Enable external and CPU caches
2-3-3-2 (69h): Initialize SMI handler
2-3-3-3 (6Ah): Display external cache size
2-3-4-1 (6Ch): Display shadow message
2-3-4-3 (6Eh): Display non-disposable segments
2-4-1-1 (70h): Display error messages
2-4-1-3 (72h): Check for configuration errors
2-4-2-1 (74h): Test real-time clock
2-4-2-3 (76h): Check for keyboard errors
2-4-4-1 (7Ch): Set up hardware interrupts vectors
2-4-4-3 (7Eh): Test coprocessor if present
3-1-1-1 (80h): Disable onboard I/O ports
3-1-1-3 (82h): Detect and install external RS232 ports
3-1-2-1 (84h): Detect and install external parallel ports
3-1-2-3 (86h): Re-initialize onboard I/O ports
3-1-3-1 (88h): Initialize BIOS data area
3-1-3-3 (8Ah): Initialize extended BIOS data area
3-1-4-1 (8Ch): Initialize floppy controller
3-2-1-1 (90h): Initialize hard-disk controller
3-2-1-2 (91h): Initialize local-bus hard-disk controller
3-2-1-3 (92h): Jump to UserPatch2
3-2-2-1 (94h): Disable A20 address line
3-2-2-3 (96h): Clear huge ES segment register
3-2-3-1 (98h): Search for option ROMs
3-2-3-3 (9Ah): Shadow option ROMs
3-2-4-1 (9Ch): Set up Power Management
3-2-4-3 (9Eh): Enable hardware interrupts
3-3-1-1 (A0h): Set time of day
3-3-1-3 (A2h): Check key lock
3-3-3-1 (A8h): Erase F2 prompt
3-3-3-3 (AAh): Scan for F2 key stroke
3-3-4-1 (ACh): Enter SETUP
3-3-4-3 (AEh): Clear in-POST flag
3-4-1-1 (B0h): Check for errors
3-4-1-3 (B2h): POST done--prepare to boot operating system
3-4-2-1 (B4h): One beep
3-4-2-3 (B6h): Check password (optional)
3-4-3-1 (B8h): Clear global descriptor table
3-4-4-1 (BCh): Clear parity checkers
3-4-4-3 (BEh): Clear screen (optional)
3-4-4-4 (BFh): Check virus and backup reminders
4-1-1-1 (C0h): Try to boot with INT 19
4-2-1-1 (D0h): Interrupt handler error
4-2-1-3 (D2h): Unknown interrupt error
4-2-2-1 (D4h): Pending interrupt error
4-2-2-3 (D6h): Initialize option ROM error
4-2-3-1 (D8h): Shutdown error
4-2-3-3 (DAh): Extended Block Move
4-2-4-1 (DCh): Shutdown error
4-2-4-3 (DEh): Keyboard Controller Failure
4-3-1-3 (E2h): Initialize the chipset
4-3-1-4 (E3h): Initialize refresh counter
4-3-2-1 (E4h): Check for Forced Flash
4-3-2-2 (E5h): Check HW status of ROM
4-3-2-3 (E6h): BIOS ROM is OK
4-3-2-4 (E7h): Do a complete RAM test
4-3-3-1 (E8h): Do OEM initialization
4-3-3-2 (E9h): Initialize interrupt controller
4-3-3-3 (EAh): Read in bootstrap code
4-3-3-4 (EBh): Initialize all vectors
4-3-4-1 (ECh): Boot the Flash program
4-3-4-2 (EDh): Initialize the boot device
4-3-4-3 (EEh): Boot code was read OK

Special thanks to PC Guide for providing a detailed and concise guide:
The PC Guide (http://www.PCGuide.com)
Site Version: 2.2.0 - Version Date: April 17, 2001
© Copyright 1997-2001 Charles M. Kozierok. All Rights Reserved.