HP e-Vectra Technical Information download pdf (Page 45)

BIOS Overview

PCI Interrupt Request Lines

PCI devices generate interrupt requests using up to eight PCI interrupt request lines. PCI interrupts can

be shared; several devices can use the same interrupt. However, optimal system performance is reached

when minimizing the sharing of interrupts.

Devices

AGP PCI1 PCI2 PCI3 AC97

Internal

LAN

USB

controller

USB

controller

SMBus

Chipset

PCI

INT

lines

PIRQA

INTA INTC

PIRQB

INTB INTD

PIRQC

INTA

PIRQD

INTB

PIRQE

INTD INTC

PIRQF

INTA INTD

PIRQG

INTB INTA

PIRQH

INTC INTB

POST Tests

The POST is executed each time the system is powered on, or a reset is performed. The POST process

verifies the basic functionality of the system components and initializes certain system parameters.

The POST starts by displaying a graphic screen of the Hewlett-Packard logo when the PC is started.

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 The POST does not detect when a hard disk drive has been otherwise 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 checkpoint codes written at the start of each test:

Checkpoint

Code

POST Routine Description

D0 NMI is Disabled. CPU ID saved. Init code Checksum verification starting.

D1 To do DMA init, Keyboard controller BAT test, start memory refresh and going to 4GB flat mode.

D3 To start Memory sizing.

D4 To comeback to real mode. Execute OEM patch. Set stack.

D5 E000 ROM enabled. Init code is copied to segment 0 and control to be transferred to segment 0.

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HP e-Vectra Technical Information Page 45

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