Error Messages and Beep Codes

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

1Refresh failure

2Parity cannot be reset

3First 64 KB memory failure

4Timer not operational

5Not used

68042 GateA20 cannot be toggled

7Exception interrupt error

8Display memory R/W error

9Not used

10CMOS Shutdown register test error

11Invalid BIOS (e.g. POST module not found, etc.)

97