Troubleshooting
6-- 62
TDS5000B Series Service Manual
BIOS Beep Codes
When an error occurs during the power on self test (POST), the BIOS displays an
error message describing the problem. 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, check the documentation for the 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 (see Table 6--10) 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 the POST completes normally, the BIOS issues one short beep before passing
control to the operating system.
Table 6--10: Beep codes
Beeps Description
1 Refresh failure
2 Parity cannot be reset
3 First 64 K memory failure
4 Timer not operational
5 Not used
6 8042 Gate A20 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 (for example, POST module not found, etc.)
PC Interface LEDs
When the oscilloscope is powered on, the PAI Loading and the Load Error LEDs
(CR700 and CR710) will turn on momentarily, and then turn off. The hard disk
activity can be monitored by observing the status of CR520.
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