Power-On Self-Tests And Error Messages; Power-On Self Test (Post); Shadow Ram - HP Vectra VL5 4 Technical Reference Manual

4 POWER-ON SELF-TESTS AND ERROR
MESSAGES
This chapter describes the power-on self-tests (POST), which are contained in the PC's ROM
BIOS, and the error messages which can result.

POWER-ON SELF TEST (POST)

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 performs the tests in the order described in this chapter.
The POST displays a graphic screen with the HP Vectra logo. If the POST detects an error, the
error message is displayed. To see the tests performed during the POST, press [ESC] when
the HP Vectra logo appears and the display will switch to text mode. In this mode, a summary
configuration screen will be displayed at the end of the POST. Pressing the PAUSE/ BREAK
key at any time will allow you to inspect the screen contents. Press any key to resume
If the POST is initiated by a soft reset [CTRL] [ALT] and [DELETE], 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.
NOTE

SHADOW RAM

On HP personal computers, access to certain ROM data is enhanced by using shadow RAM.
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. This technique provides faster access to the
system BIOS firmware.
POST Test
LED Test
Processor Test
System (BIOS) ROM Test
RAM Refresh Timer Test
Interrupt RAM Test
Shadow the System ROM BIOS
The POST does not detect when a slave hard disk
drive ("HDD 1" or "HDD 3" in the setup) has been
installed or changed.
Description
System BIOS Tests
Tests the LEDs on the control panel.
Tests the processor's registers. Test failure causes the boot
process to abort.
Calculates an 8-bit checksum. Test failure causes the boot
process to abort.
Tests the RAM refresh timer circuitry. Test failure causes the
boot process to abort.
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.
Tests the system ROM BIOS and shadows it. Failure to
shadow the ROM BIOS will cause an error code to display.
The boot process will continue, but the system will execute
from ROM. This test is not performed after a soft reset (using
[CTRL] [ALT] and [DELETE]).