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BIOS Overview
Evo D310 Micro Desktop 47
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.
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
F4
.
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:
Chipset
PCI INT
lines
Devices
AGP PCI1 PCI2 PCI3 AC97
Internal
LAN
USB
controller
1
USB
controller
2
USB
controller
3
SMBus
PIRQA
INTA INTB
PIRQB
INTB INTC
PIRQC
INTD
PIRQD
INTA
PIRQE
INTD INTC
PIRQF
INTA INTD
PIRQG
INTB INTA
PIRQH
INTC INTB
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.