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5 Power-On Self-Test and Error Messages
Order in Which the Tests are Performed
Order in Which the Tests are Performed
Each time the system is powered on, or a reset is performed, the POST is
executed. The POST process verifies the basic functionality of the system
components and initializes certain system parameters.
The POST starts by displaying a graphic screen with the initial “Vectra” logo
when the PC is restarted. If the POST detects an error, the error message is
displayed inside a view system errors screen, in which the error message
utility (EMU) not only displays the error diagnosis, but the suggestions for
corrective action (see page 89 for a brief summary). Error codes are no
longer displayed.
Devices, such as memory and newly installed hard disks, are configured
automatically. The user is not requested to confirm the change. Newly
removed hard disks are detected, and the user is prompted to confirm the
new configuration by pressing . Note, though, that the POST does not
detect when a hard disk drive has been changed.
During the POST, the BIOS and other ROM data is copied into high-speed
shadow RAM. The shadow RAM is addressed at the same physical location
as the original ROM in a manner which is completely transparent to
applications. It therefore appears to behave as very fast ROM. This
technique provides faster access to the system BIOS firmware.
The following table lists the POST routines in the order in which they are
executed (from the shadow RAM). If the POST is initiated by a soft reset
and , the RAM tests are not executed and shadow RAM is
not cleared. In all other respects, the POST executes in the same way
following power-on or a soft reset.
Test Description
System BIOS Tests
LED Test
Tests the LEDs on the control panel.
System (BIOS) ROM Test
Calculates an 8-bit checksum. Test failure causes the boot process to abort.
RAM Refresh Timer Test
Tests the RAM refresh timer circuitry. Test failure causes the boot process
to abort.
Interrupt RAM Test
Checks the first 64 KB of system RAM used to store data corresponding to
various system interrupt vector addresses. Test failures cause the boot
process to abort.
Delete
