Microsoft KB Archive/246236

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How to Upgrade Windows 2000 to Use an ACPI HAL

Article ID: 246236

Article Last Modified on 3/1/2007


  • Microsoft Windows 2000 Server
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional Edition

This article was previously published under Q246236


This article describes how to configure your computer to use either a standard APM hardware abstraction layer (HAL) or an ACPI enabled HAL.


To change the Standard HAL to ACPI HAL, use Winnt32.exe to install Windows 2000 over the current installation. If you try to change the type of HAL without running Setup, you may not be able to start Windows successfully again or you may experience hardware and other stability problems.

You cannot change between Standard and ACPI HALs because of the different way an ACPI and a non-ACPI BIOS enumerate hardware. The copy of the hardware tree, which is kept in the registry, is stored differently for each type of HAL. If you change the HAL without running Setup again, Windows may not be able to find hardware components needed to start the computer.

NOTE: You can use Device Manager to change from a single-processor HAL to a multiple-processor HAL.

For additional information, see the following article or articles in the Microsoft Knowledge Base:

237556 Troubleshooting Windows 2000 Hardware Abstraction Layer Issues

216573 How Windows 2000 Determines ACPI Compatibility

197055 Disabling ACPI Support in BIOS Results in Error Message

Keywords: kbenv kbhardware kbhowto kbsetup KB246236