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How to Enable ACPI Support in Windows 98

ACPI (Advanced Configuration and Power Interface) is an open industry specification co-developed by Compaq, Intel, Microsoft, Phoenix, and Toshiba.

To enable ACPI support in Windows 98, you must have an ACPI- compatible motherboard and an ACPI 1.0-compliant Basic Input/Output System (BIOS).

To enable ACPI support on your Windows 98, or Windows 98 SE system, you need to use either of the following methods:


Reinstall Windows 98 using the /p j command-line switch. This adds the ACPIOption string value with a value data of 1 to the registry. To run Windows 98 Setup using the /p j command-line switch, click Start > Run, and type the following command in the Open box, and then click OK:

setup /p j

Reinstalling Windows 98 is the best way to ensure that all devices are configured correctly.

Change the registry

Force ACPI detection by manually adding the ACPIOption string value to the registry, and then use the Add New Hardware tool in Control Panel to redetect your computer's hardware. To do so, follow these steps:

  1. Since your CD-ROM drive is disabled by the Plug and Play BIOS during hardware detection, manually copy the Windows 98 cabinet (.cab) files from the Windows 98 CD-ROM to your hard disk. To do so, follow these steps:

    • Create a new folder on your hard disk (let's call it Win98cab)
    • Copy the contents of the Win98 folder on the Windows 98 CD-ROM to the Win98cab folder you created
    • Start the Registry Editor
    • Go to HKEY_LOCAL_MACHINE \ Software \ Microsoft \ Windows \CurrentVersion \ Detect
    • In the right-hand pane right-click an empty space and choose New > DWORD Value
    • Name it ACPIOption, double-click it, and change the value to 1
    • Close the registry editor

  2. Select Start > Settings > Control Panel, and then double-click Add New Hardware
  3. Click Next, click Next again, click Yes (Recommended), and then click Next. ACPI should be detected and installed. After your computer is restarted, all ACPI-enumerated devices are set up again.

    Note: If you are prompted for files that the Add New Hardware Wizard cannot find, click Cancel or click Browse and locate the folder to which you copied the Windows 98 .cab files. Do not click Skip File, as this can cause Windows 98 to stop responding (hang) when you restart your computer and require you to reinstall Windows 98.

If there are duplicate entries in Device Manager after enabling ACPI, click a duplicate device that is not showing a conflict, and then click Remove.

For example, if two video adapters are listed, one has a resource conflict indicated by an exclamation point in a yellow circle next to the device. Remove the working video adapter and restart your computer. The device with the resource conflict is the one that should now be running in ACPI mode.

Note: After using method 2 to enable ACPI support, some devices may still detect a conflicting counterpart even after you remove them. If the device is working correctly, use method 1 to reinstall Windows 98 using the /p j command-line switch.

Before running either method, use ScanReg to make a backup of your registry. ACPI is not a fully mature standard, and any little bug in your BIOS or system drivers are going to have you want to uninstall ACPI support. If you want to uninstall ACPI support, just restore the registry backup you made prior to enabling ACPI on your system.

ACPI Errors

When Windows 98 boots, you may get a red or blue screen with an ACPI error code.

Red screens indicate that the problem is probably related to a hardware or BIOS problem. Blue screens indicate that the problem is probably related to software or is an obscure problem.

  • An error code on a red or blue screen with the format 1xxx indicates an error during initialization phase of the ACPI driver and usually means the driver cannot read one or more of the ACPI ables.
  • An error code with the format 2xxx indicates an ACPI machine language (AML) interpreter error.
  • An error code with the format 3xxx indicates an error within the ACPI driver event handler, usually when the event handler is running a control method as the result of a general-purpose event (GPE).

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