Mitac 8080 Service Manual - laptop schematics, notebook ...

7. Maintenance Diagnostics
7.1 Introduction
8080 N/B Maintenance
Each time the computer is turned on, the system bios runs a series of internal checks on the hardware. This
power-on self test (post) allows the computer to detect problems as early as the power-on stage. Error
messages of post can alert you to the problems of your computer.
If an error is detected during these tests, you will see an error message displayed on the screen. If the error
occurs before the display is initialized,then the screen cannot display the error message. Error codes or
system beeps are used to identify a post error that occurs when the screen is not available.
The value for the diagnostic port (378H) is written at the beginning of the test. Therefore, if the test failed,
the user can determine where the problem occurred by reading the last value written to port 378H by the
378H port debug board plug at PIO PORT.
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