Whenever a recoverable error occurs during POST, the BIOS displays an error message
describing the problem (see Table 53). 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.
18.April.2014
18.April.2014
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