Computer POST and Beep Codes

The computer POST (power-on self-test) checks a computer's internal hardware for compatibility and connection before starting the remainder of the boot process.

If the computer passes the POST, the computer may give a single beep (some computers may beep twice) as it starts and continue to boot. However, if the computer fails the POST, the computer will either not beep or generate a beep code that tells the user the source of the problem.

Contents

Macintosh

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

Award BIOS

    Beeps     Error
1 long, 2 short Video error, the BIOS cannot initialize the video screen
1 long, 3 short Video card not detected or bad video card
Beeps repeating endlessly RAM problem
High frequency beeps while running Overheating processor
Alternating high & low frequency Issue with the processor, possibly damaged

Phoenix BIOS

    Beeps     Error
1-1-1-1 Unconfirmed (reset RAM or replace RAM)
1-1-1-3 Verify real mode
1-1-2-1 Get CPU type
1-1-2-3 Initialize system hardware
1-1-3-1 Initialize chipset registers with initial POST values
1-1-3-2 Set in POST flag
1-1-3-3 Initialize CPU registers
1-1-4-1 Initialize cache to initial POST values
1-1-4-3 Initialize I/O
1-2-1-1 Initialize power management
1-2-1-2 Load alternate registers with initial POST values
1-2-1-3 Jump to UserPatch0
1-2-2-1 Initialize keyboard controller
1-2-2-3 BIOS ROM checksum
1-2-3-1 8254 timer initialization
1-2-3-3 8237 DMA controller initialization
1-2-4-1 Reset programmable interrupt controller
1-3-1-1 Test DRAM refresh
1-3-1-3 Test 8742 keyboard controller
1-3-2-1 Set ES segment to register to 4 GB
1-3-3-1 Autosize DRAM
1-3-3-3 Clear 512 K base RAM
1-3-4-1 Test 512 base address lines
1-3-4-3 Test 512 K base memory
1-4-1-3 Test CPU bus clock frequency
1-4-2-4 Reinitialize the chipset
1-4-3-1 Shadow system BIOS ROM
1-4-3-2 Reinitialize the cache
1-4-3-3 Autosize cache
1-4-4-1 Configure advanced chipset registers
1-4-4-2 Load alternate registers with CMOS values
2-1-1-1 Set initial CPU speed
2-1-1-3 Initialize interrupt vectors
2-1-2-1 Initialize BIOS interrupts
2-1-2-3 Check ROM Copyright notice
2-1-2-4 Initialize manager for PCI options ROMs
2-1-3-1 Check video configuration against CMOS
2-1-3-2 Initialize PCI bus and devices
2-1-3-3 Initialize all video adapters in system
2-1-4-1 Shadow video BIOS ROM
2-1-4-3 Display Copyright notice
2-2-1-1 Display CPU type and speed
2-2-1-3 Test keyboard
2-2-2-1 Set key click if enabled
2-2-2-3 Enable keyboard
2-2-3-1 Test for unexpected interrupts
2-2-3-3 Display prompt Press F2 to enter SETUP
2-2-4-1 Test RAM between 512 and 640 k
2-3-1-1 Test expanded memory
2-3-1-3 Test extended memory address lines
2-3-2-1 Jump to UserPatch1
2-3-2-3 Configure advanced cache registers
2-3-3-1 Enable external and CPU caches
2-3-3-3 Display external cache size
2-3-4-1 Display shadow message
2-3-4-3 Display non-disposable segments
2-4-1-1 Display error messages
2-4-1-3 Check for configuration errors
2-4-2-1 Test real-time clock
2-4-2-3 Check for keyboard errors
2-4-4-1 Set up hardware interrupts vectors
2-4-4-3 Test coprocessor if present
3-1-1-1 Disable onboard I/O ports
3-1-1-3 Detect and install external RS232 ports
3-1-2-1 Detect and install external parallel ports
3-1-2-3 Re-initialize onboard I/O ports
3-1-3-1 Initialize BIOS data area
3-1-3-3 Initialize extended BIOS data area
3-1-4-1 Initialize floppy controller
3-2-1-1 Initialize hard disk controller
3-2-1-2 Initialize local bus hard disk controller
3-2-1-3 Jump to UserPatch2
3-2-2-1 Disable A20 address line
3-2-2-3 Clear huge ES segment register
3-2-3-1 Search for option ROMs
3-2-3-3 Shadow option ROMs
3-2-4-1 Set up Power Management
3-2-4-3 Enable hardware interrupts
3-3-1-1 Set time of day
3-3-1-3 Check key lock
3-3-3-1 Erase F2 prompt
3-3-3-3 Scan for F2 key stroke
3-3-4-1 Enter CMOS setup
3-3-4-3 Clear in POST flag
3-4-1-1 Check for errors
3-4-1-3 POST done, prepare to boot operating system
3-4-2-1 One beep
3-4-2-3 Check password (optional)
3-4-3-1 Clear global descriptor table
3-4-4-1 Clear parity checkers
3-4-4-3 Clear screen (optional)
3-4-4-4 Check virus and backup reminders
4-1-1-1 Try to boot with INT 19
4-2-1-1 Interrupt handler error
4-2-1-3 Unknown interrupt error
4-2-2-1 Pending interrupt error
4-2-2-3 Initialize option ROM error
4-2-3-1 Shutdown error
4-2-3-3 Extended block move
4-2-4-1 Shutdown 10 error
4-3-1-3 Initialize the chipset
4-3-1-4 Initialize refresh counter
4-3-2-1 Check for forced flash
4-3-2-2 Check HW status of ROM
4-3-2-3 BIOS ROM is OK
4-3-2-4 Do a complete RAM test
4-3-3-1 Do OEM initialization
4-3-3-2 Initialize interrupt controller
4-3-3-3 Read in bootstrap code
4-3-3-4 Initialize all vectors
4-3-4-1 Boot the flash program
4-3-4-2 Initialize the boot device
4-3-4-3 Boot code was read OK
two-tone siren Low CPU speed, voltage level issue

AMI BIOS

    Beeps     Error
1 short DRAM refresh failure
2 short Parity circuit failure
3 short Base 64 K RAM failure
4 short System timer failure
5 short Process failure
6 short Keyboard controller Gate A20 error
7 short Virtual mode exception error
8 short Display memory Read/Write test failure
9 short ROM BIOS checksum failure
10 short CMOS shutdown Read/Write error
11 short Cache memory error
1 long 3 short Conventional/Extended memory failure
1 long 8 short Display/Retrace test failed
two-tone siren Low CPU fan speed / voltage level issue

IBM BIOS

    Beeps     Error
No beeps No power, loose card, or short
1 short beep Normal POST, computer is ok
2 short beep POST error, review screen for error code
Continuous beep No power, loose card, or short
Repeating short beep No power, loose card, or short
1 long and 1 short beep Motherboard issue
1 long and 2 short beeps Video (Mono/CGA display circuitry) issue
1 long and 3 short beeps Video (EGA) display circuitry
3 long beeps Keyboard or keyboard card error
1 beep, blank or incorrect display Video display circuitry

Dell BIOS

    Beeps     Error
1 beep ROM corruption or failure
2 beeps Memory (RAM) not detected
3 beeps Motherboard failure
4 beeps Memory (RAM) failure
5 beeps CMOS battery failure
6 beeps Video card failure
7 beeps Bad processor (CPU)
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