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Error Messages and Beep Codes
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5.5 BIOS Beep Codes
Whenever a recoverable error occurs during power-on self-test (POST), the BIOS displays an error
message describing the problem (see Table 65). The BIOS also issues a beep code (one long tone
followed by two short tones) during POST if the video configuration fails (a faulty video card or
no card installed) or if an external ROM module does not properly checksum to zero.
An external ROM module (for example, a video BIOS) can also issue audible errors, usually
consisting of one long tone followed by a series of short tones. For more information on the beep
codes issued, check the documentation for that external device.
There are several POST routines that issue a POST terminal error and shut down the system if they
fail. Before shutting down the system, the terminal-error handler issues a beep code signifying the
test point error, writes the error to I/O port 80h, attempts to initialize the video and writes the error
in the upper left corner of the screen (using both monochrome and color adapters).
If POST completes normally, the BIOS issues one short beep before passing control to the
operating system.
Table 65. Beep Codes
Beep Description
1 Refresh failure
2 Parity cannot be reset
3 First 64 KB memory failure
4 Timer not operational
5 Not used
6 8042 GateA20 cannot be toggled
7 Exception interrupt error
8 Display memory R/W error
9 Not used
10 CMOS Shutdown register test error
11 Invalid BIOS (e.g. POST module not found, etc.)