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.
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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