PNP Setup

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PNP / PCI Configuration

The following sections describe the fields and options found in the PnP /PCI Configuration page of the setup utility.

PnP OS Installed

If the operating system supports Plug & Play (PnP) the user can let that take over the management of device resources. If a non-PnP-aware OS or not all of the operating systems (multiple OS installed) support PnP, then let the BIOS handle it management a device resources.

Yes: let operating system control PnP.
No: let the BIOS handle PnP management.

Force Update ESCD / Reset Configuration Data

This option enables resetting ESCD. Extended System Configuration Data is a feature of the Plug and Play BIOS that stores the IRQ, DMA, I/O and memory configurations of all the ISA, PCI and AGP cards in the system, PnP or legacy. If a new expansion card is installed and the system configuration causes serious conflicts the OS may not boot, enable this field so that the BIOS will reset and reconfigure the settings for all PnP cards in the system during bootup.

Enabled: Reset the configuration data for all PnP cards.
Disabled: The Bios automatically resets this on reboot if changed.

Resource Controlled By

The BIOS has the capability to automatically configure all of the boot and Plug and Play compatible devices. If there are problems assigning the resources automatically via the BIOS, manual to reveal the IRQ and DMA assignment fields. Then assign each IRQ or DMA channel to either Legacy ISA or PCI/ISA PnP devices.
Legacy ISA devices are compliant with the original PC AT bus specification and require a specific interrupt / DMA channel to function properly. PCI/ISA PnP devices adhere to the Plug and Play standard and can use any interrupt / DMA channel.

Auto: the BIOS can automatically assign the IRQs and DMA channels.
Manual: If there are problems assigning the resources automatically.

Assign IRQ For VGA

Most modern graphics cards require an IRQ to function properly. Disabling this feature with such cards will cause improper operation and/or poor performance.

Enabled: For most modern graphics cards.
Disabled: disable this feature to release an IRQ for other uses.

Assign IRQ For USB

This field enables or disables IRQ allocation for the USB (Universal Serial Bus).

Enabled: If using a USB device. Also when first installing windows 9x operating systems.
Disabled: To free up an IRQ for other devices to use.

Assign IRQ For ACPI

This field enables or disables IRQ allocation for the ACPI (Advanced Configuration and Power Interface).

Enabled: Assign IRQ for ACPI
Disabled: Do not assign IRQ for ACPI. Frees up an IRQ.

If the system does not fully support ACPI, all applications, device drivers, and hardware, then this option is best set to disabled. Pmtshoot.exe is a utility to check and report what is stopping the computer from successfully using power management mode. It requires a bit of experimenting to use ACPI and the idea is good, but sometimes the machine just locks and never returns to full power mode and other times applications lock or data gets corrupted.

PCI IRQ Activated By

This BIOS option allows setting the method by which the IRQ for PCI cards are activated / triggered. ISA and old PCI cards are Edge triggered (using a single voltage) while newer PCI and AGP cards are Level triggered (using multiple voltage levels). When PCI devices were first available, the best setting was Edge because no PCI devices supported IRQ sharing, but now almost every PCI device supports IRQ sharing.

Edge: If using old edge-triggered PCI cards.
Level: PCI devices can share IRQs.

CPU To PCI Write Buffer

When this field is enabled, writes from the CPU to the PCI bus are buffered, to compensate for the speed differences between the CPU and the PCI bus. When disabled the writes are not buffered and the CPU must wait until the write is complete before starting another write cycle.

Enabled: Buffered writes to the PCI bus. Speeds up execution in the CPU.
Disabled: Writes are not buffered. More reliable but slower.

PCI Dynamic Bursting

When enabled every write transaction goes to the write buffer. Burstable transactions then burst on the PCI bus and non burstable transactions don't. This option combines several PCI cycles into one.

Enabled: Enhances the system performance, but may reduce reliability.
Disabled: Improves system reliability. Reduces system performance.

PCI Master 0 WS Write

Enabling this field in the BIOS increases the write cycle speed on the PCI bus by reducing the delay that the PCI device waits before starting to write on the PCI bus.

Enabled: Increases system performance, but may become unstable.
Disabled: Better system performance, but slower.

PCI Master Read Prefetch

Set this option to enable reading prefetch for the PCI bus. When this field is set the system is allowed to prefetch the next read and initiate the next process.

Enabled: Enhances PCI bus performance.
Disabled: No prefetch is performed on the PCI bus.

PCI #2 Access #1 Retry

This item enables PC#2 (AGP) Access #1 (PCI) attempts if an error occurs.

Enabled:
Disabled:

PCI Master Broken Timer

Setting this option to enabled allows for slower PCI bus mastering expansion cards.