Post Beep Codes - By Gene Goldring

Every time a computer is switched on it performs a short diagnostic routine known as the POST, or Power On Self Test. The POST is a small program contained in the BIOS. It checks that basic hardware is present and performs a rudimentary memory test. The POST announces the results of its routine both audibly (a series of beeps on the PC speaker) and visually (displaying a brief summary or codes on the screen). The audible method is essential since a fault may exist with the graphics card or monitor. If all is well, the computer typically emits a single beep and carries on booting. The number and duration of the beeps is intended as a coded message and understanding them will allow you to diagnose any problems the computer may have.

The codes vary according to the manufacturer of the BIOS.
Here are some of the more common codes:

**AMI BIOS**
Number	Duration of Beeps

1 short	DRAM refresh failure (Problem with memory)
2 short	Parity circuit failure
3 short	Base 64K RAM failure
4 short	System Timer failure
5 short	Processor failure
6 short	Keyboard Controller / Gate A20 failure
7 short	Virtual Mode Exception error
8 short	Display Memory Read/Write failure (video card fault)
9 short	ROM BIOS Checksum error (BIOS chip fault)
10 short	CMOS Shutdown Read/Write error
11 short	Cache memory
1 long	Passed (no errors)
1 long/2 short	Video failure
1 long/3 short	Base / Extended Memory failure
1 long/8 short	Display / Retrace Test failure

**Award BIOS**
Number	Duration of Beeps

1 short	Passed (no errors)
2 short	Any non-fatal error
1 long/2 short	Video failure
1 long/3 short	Keyboard Controller failure (applies to 286/386/486)

**IBM BIOS**
Number	Duration of Beeps

none	Power Supply or System Board failure (possible short)
1 short	Passed (no errors)
1 short	(blank screen) Video error (check cable)
1 short	(no boot) Floppy Drive error
2 short	Configuration Error (displayed on screen)
repeated short	Power Supply or System Board failure
continuous	Power Supply or System Board/Keyboard stuck
1 long/1 short	System Board failure
1 long/2 short	Video (Mono/CGA) failure (check cable)
1 long/3 short	Video (EGA) failure (check cable)
3 long	Keyboard Card error

**Phoenix BIOS**
Number	Duration of Beeps

1/1/3	CMOS Read/Write
1/1/4	ROM BIOS Checksum failure
1/2/1	Programmable Interval Timer failure
1/2/2	DMA Initialisation failure
1/2/3	DMA Page Register Read/Write failure
1/3/1	RAM Refresh Verification error
1/3/3	First 64K RAM Chip/Data Line failure
1/3/4	First 64K RAM Odd/Even Logic
1/4/1	First 64K RAM: Address Line
1/4/2	First 64K RAM: Parity failure
1/4/3	Fail-Safe Timer Feature (EISA only)
1/4/4	Software NMI Port failure (EISA only)
4/2/4	Unexpected Interrupt in Protected Mode
2/followed by various combinations
	First 64K RAM Chip/Data Line failure (combinations indicate which bit)
3/1/1	Slave DMA Register failure
3/1/2	Master DMA Register failure
3/1/3	Master Interrupt Mask Register failure
3/1/4	Slave Interrupt Mask Register failure
3/2/4	Keyboard Controller failure
3/3/4	Display Memory failure
3/4/1	Display Retrace failure
3/4/2	Video ROM search proceeding
4/2/1	Timer Tick failure
4/2/2	Shutdown failure
4/2/3	Gate A20 failure
4/3/1	RAM test above 64K failure
4/3/2/3	Programmable Interval Timer, Channel 2 failure
4/3/4	Realtime Clock failure
4/4/1	Serial Port error
4/4/2	Parallel Port error
4/4/3	Math Co-processor failure
(tone) 1/1/2	System Board Select
(tone) 1/1/3	Extender CMOS RAM

Beemer's Tutorials...

For information on health, wealth building and personal development, click here.