Debug Leds - SOYO SY-7VCA User Manual

Hardware Installation

2-3.9 Debug LEDs

The Debug LEDs give an indication of the status of the system during boot-up. If
the system does not boot-up properly, use the table below to find out at what point
in boot-up sequence the problem arises. A x means the LED is off, a L means the
LED is lit.
Code Explanation
Initialization of the chipset. The MCH and ICH registers will be set to the
X X X L
most conservative values by the BIOS to make sure the system boots up
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properly.
The BIOS is now decompressing the BIOS code into shadow RAM. Most of
X X L X
the BIOS code is stored in the BIOS Flash ROM IC in compressed form to
save space. At boot-up this code is decompressed and stored to RAM for faster
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execution.
The checksum for the decompressed code is calculated and checked. The
X X L L
checksum is calculated by adding all data bytes together and storing the result
in the BIOS ROM. If the calculated checksum is different from the checksum
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stored in the ROM, the code stored in the FLASH ROM is corrupted.
The chipset (MCH and ICH) registers are set to the values selected by the user.
X L X X
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Now the BIOS will set the CPU Vcore voltage and the FSB bus frequency to
X L X L
the user selected value. If the system stops at this point, the settings selected
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by the user are inappropriate. Please select more conservative settings.
The Hardware Monitor Functionality is initialized. The settings the user
X L L X
selected in the BIOS for the Hardware Monitor are written into the Hardware
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Monitor registers.
If the VGA card does not work or is not inserted at all, the system will display
X L L L
this code for a short period of time.
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At this point the BIOS is initializing the CPU. The L2 cache latency values are
L X X X
set, and more important, the CPU micro-code is written into the CPU.
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Now the system is testing the RAM inserted on the board. The screen will
L X X L
show the BIOS testing the RAM by a running counter. After finishing the test,
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the screen will show the amount of RAM in your system.
The super I/O registers are set to the default values. This includes the serial,
L X L X
parallel and IR etc settings.
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At this point the IDE busses (primary and secondary) are scanned for devices.
L X L L
This includes HD drives and ATAPI CD-ROM drives that are connected to the
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IDE bus. After scanning the detected devices are displayed on screen.
The serial and parallel port registers are set to the values selected by the user.
L L X X
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Now the BIOS will scan the peripheral busses for add-on cards. This includes
L L X L
the PCI and AGP busses. If any add-on cards are detected, the resources it
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requires are assigned by the BIOS in accordance with user settings.
The ESCD and DMI (Desktop Management Interface) values are checked. If
L L L X
there are changes, the BIOS will flash the new values into the BIOS Flash
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ROM IC.
At this point the BIOS passes control to the Operating System (OS). All LEDs
L L L L
will be on and will stay on to indicate a successful boot.
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SY-7VCA