Chapter 3 - BIOS POST
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B e e p C o d e s
B e e p C o d e s
Errors can occur during POST (Power On Self Test), performed every time the system is powered on. Fatal errors are
communicated through a series of audible beeps. Fatal errors do not allow the system to continue the boot process. Consult the
component manufacturer for possible repairs if a fatal error occurs.
If the BIOS can initialize the system video display, it displays error messages. Often, these messages (listed on page 25) allow the
system to continue to boot.
A M I B I O S B e e p C o d e s
A M I B I O S B e e p C o d e s
Beeps
Error message
Description
1
Refresh Failure
The memory refresh circuitry on the
motherboard is faulty.
2
Parity Error
Parity error in the first 64 KB memory block.
3
Base 64 KB Memory
Failure
Memory failure in the first 64 KB memory
block.
4
Timer Not Operational
Memory failure in the first 64 KB of memory,
or Timer Number1 on the motherboard is not
functioning.
5
Processor error
The CPU on the motherboard generated an
error.
6
8042 - Gate A20 Failure
Gate A20 on the keyboard controller (8042)
allows the CPU to operate in protected mode.
The BIOS cannot switch to protected mode.
7
Processor Exception
Interrupt Error
The CPU on the motherboard has generated
an exception interrupt.
8
Display Memory
Read/Write Error
The system video adapter is either missing or
its memory is faulty. This is not a fatal error.
9
ROM Checksum Error
The ROM checksum value does not match the
value encoded in the BIOS.
10
CMOS Shutdown Register
Read/Write Error
The shutdown register for CMOS RAM has
failed.
11
Cache memory error
Cache memory is the wrong type or is not
properly configured.